Inkjet print head recapping mechanism

ABSTRACT

A print head recapping mechanism is disclosed for recapping a page width ink jetting print head structure, comprising a first stationary ferrous arm; a solenoid coil wrapped around a portion of the ferrous arm; a second moveable arm located substantially adjacent the first arm and biased towards the print head structure; a series of membranes attached to the second moveable arm the membranes sealing the print head structure when in a rest position; the solenoid being activated to cause the moveable arm to move away from the surface of the print head structure sufficient to allow a “paper or film” to be inserted between the membranes and the print head structure for the printing of ink thereon. Preferably, the membranes are resiliently collapsible against the surface of the print head structure. The membranes can comprise two mutually opposed elastomer strips running substantially the length of the ink jetting portions of the print head structure so as to surround the ink jetting portions. The solenoid can include an elongated winding of a current carrying wire which is wrapped around a protruding portion of the first arm, the elongation being substantially the length of the print head structure.

CROSS REFERENCES TO RELATED APPLICATIONS

The following Australian provisional patent applications are herebyincorporated by cross-reference. For the purposes of location andidentification, US patent applications identified by their US patentapplication serial numbers (USSN) are listed alongside the Austalianapplications from which the US patent applications claim the right ofpriority.

U.S. Pat. No./PATENT APPLICATION CROSS-REFERENCED AUSTRALIAN FILED ONJULY 10, 1998 PROVISIONAL PATENT APPLICATION (CLAIMING RIGHT OF PRIORITYFROM NO. AUSTRALIAN PROVISIONAL APPLICATION) DOCKET NO. PO7991 (filed 15July 1997) 09/113,060 ART01 PO7988 (filed 15 July 1997) 09/113,070 ART02PO7993 (filed 15 July 1997) 09/113,073 ART03 PO9395 (filed 15 July 1997)09/112,748 ART04 PO8017 (filed 15 July 1997) 09/112,747 ART06 PO8014(filed 15 July 1997) 09/112,776 ART07 PO8025 (filed 15 July 1997)09/112,750 ART08 PO8032 (filed 15 July 1997) 09/112,746 ART09 PO7999(filed 15 July 1997) 09/112,743 ART10 PO7998 (filed 15 July 1997)09/112,742 ART11 PO8031 (filed 15 July 1997) 09/112,741 ART12 PO8030(filed 15 July 1997) 09/112,740 ART13 PO7997 (filed 15 July 1997)09/112,739 ART15 PO7979 (filed 15 July 1997) 09/113,053 ART16 PO8015(filed 15 July 1997) 09/112,738 ART17 PO7978 (filed 15 July 1997)09/113,067 ART18 PO7982 (filed 15 July 1997) 09/113,063 ART19 PO7989(filed 15 July 1997) 09/113,069 ART20 PO8019 (filed 15 July 1997)09/112,744 ART21 PO7980 (filed 15 July 1997) 09/113,058 ART22 PO8018(filed 15 July 1997) 09/112,777 ART24 PO7938 (filed 15 July 1997)09/113,224 ART25 PO8016 (filed 15 July 1997) 09/112,804 ART26 PO8024(filed 15 July 1997) 09/112,805 ART27 PO7940 (filed 15 July 1997)09/113,072 ART28 PO7939 (filed 15 July 1997) 09/112,785 ART29 PO8501(filed 11 Aug 1997) 09/112,797 ART30 PO8500 (filed 11 Aug 1997)09/112,796 ART31 PO7987 (filed 15 July 1997) 09/113,071 ART32 PO8022(filed 15 July 1997) 09/112,824 ART33 PO8497 (filed 11 Aug 1997)09/113,090 ART34 PO8020 (filed 15 July 1997) 09/112,823 ART38 PO8023(filed 15 July 1997) 09/113,222 ART39 PO8504 (filed 11 Aug 1997)09/112,786 ART42 PO8000 (filed 15 July 1997) 09/113,051 ART43 PO7977(filed 15 July 1997) 09/112,782 ART44 PO7934 (filed 15 July 1997)09/113,056 ART45 PO7990 (filed 15 July 1997) 09/113,059 ART46 PO8499(filed 11 Aug 1997) 09/113,091 ART47 PO8502 (filed 11 Aug 1997)09/112,753 ART48 PO7981 (filed 15 July 1997) 09/113,055 ART50 PO7986(filed 15 July 1997) 09/113,057 ART51 PO7983 (filed 15 July 1997)09/113,054 ART52 PO8026 (filed 15 July 1997) 09/112,752 ART53 PO8027(filed 15 July 1997) 09/112,759 ART54 PO8028 (filed 15 July 1997)09/112,757 ART56 PO9394 (filed 23 Sep 1997) 09/112,758 ART57 PO9396(filed 23 Sep 1997) 09/113,107 ART58 PO9397 (filed 23 Sep 1997)09/112,829 ART59 PO9398 (filed 23 Sep 1997) 09/112,792 ART60 PO9399(filed 23 Sep 1997) 6,106,147 Publication date Aug 22, 2000 ART61 PO9400(filed 23 Sep 1997) 09/112,790 ART62 PO9401 (filed 23 Sep 1997)09/112,789 ART63 PO9402 (filed 23 Sep 1997) 09/112,788 ART64 PO9403(filed 23 Sep 1997) 09/112,795 ART65 PO9405 (filed 23 Sep 1997)09/112,749 ART66 PP0959 (filed 16 Dec 1997) 09/112,784 ART68 PP1397(filed by Jan 1998) 09/112,783 ART69 PP2370 (filed 16 Mar 1998)09/112,781 DOT01 PP2371 (filed 16 Mar 1998) 09/113,052 DOT02 PO8003(filed 15 Jul 1997) 09/112,834 Fluid01 PO8005 (filed 15 Jul 1997)09/113,103 Fluid02 PO9404 (filed 23 Sep 1997) 09/113,101 Fluid03 PO8066(filed 15 Jul 1997) 09/112,751 IJ01 PO8072 (filed 15 Jul 1997)09/112,787 IJ02 PO8040 (filed 15 Jul 1997) 09/112,802 IJ03 PO8071 (filed15 Jul 1997) 09/112,803 IJ04 PO8047 (filed 15 Jul 1997) 09/113,097 IJ05PO8035 (filed 15 Jul 1997) 09/113/099 IJ06 PO8044 (filed 15 Jul 1997)09/113,084 IJ07 PO8063 (filed 15 Jul 1997) 09/113,066 IJ08 PO8057 (filed15 Jul 1997) 09/112,778 IJ09 PO8056 (filed 15 Jul 1997) 09/112,779 IJ10PO8069 (filed 15 Jul 1997) 09/113,077 IJ11 PO8049 (filed 15 Jul 1997)09/113,061 IJ12 PO8036 (filed 15 Jul 1997) 09/112,818 IJ13 PO8048 (filed15 Jul 1997) 09/112,816 IJ14 PO8070 (filed 15 Jul 1997) 09/112,772 IJ15PO8067 (filed 15 Jul 1997) 09/112,819 IJ16 PO8001 (filed 15 Jul 1997)09/112,815 IJ17 PO8038 (filed 15 Jul 1997) 09/113,096 IJ18 PO8033 (filed15 Jul 1997) 09/113,068 IJ19 PO8002 (filed 15 Jul 1997) 09/113,095 IJ20PO8068 (filed 15 Jul 1997) 09/112,808 IJ21 PO8062 (filed 15 Jul 1997)09/112,809 IJ22 PO8034 (filed 15 Jul 1997) 09/112,780 IJ23 PO8039 (filed15 Jul 1997) 09/113,083 IJ24 PO8041 (filed 15 Jul 1997) 09/113,121 IJ25PO8004 (filed 15 Jul 1997) 09/113,122 IJ26 PO8037 (filed 15 Jul 1997)09/112,793 IJ27 PO8043 (filed 15 Jul 1997) 09/112,794 IJ28 PO8042 (filed15 Jul 1997) 09/113,128 IJ29 PO8064 (filed 15 Jul 1997) 09/113,127 IJ30PO9389 (filed 23 Sep 1997) 09/112,756 IJ31 PO9391 (filed 23 Sep 1997)09/112,755 IJ32 PP0888 (filed 12 Dec 1997) 09/112,754 IJ33 PP0891 (filed12 Dec 1997) 09/112,811 IJ34 PP0890 (filed 12 Dec 1997) 09/112,812 IJ35PP0873 (filed 12 Dec 1997) 09/112,813 IJ36 PP0993 (filed 12 Dec 1997)09/112,814 IJ37 PP0890 (filed 12 Dec 1997) 09/112,764 IJ38 PP1398 (filed19 Jan 1998) 09/112,765 IJ39 PP2592 (filed 25 Mar 1998) 09/112,767 IJ40PP2593 (filed 25 Mar 1998) 09/112,768 IJ41 PP3991 (filed 9 Jun 1998)09/112,807 IJ42 PP3987 (filed 9 Jun 1998) 09/112,806 IJ43 PP3985 (filed9 Jun 1998) 09/112,820 IJ44 PP3983 (filed 9 Jun 1998) 09/112,821 IJ45PO7935 (filed 15 Jul 1997) 09/112,822 IJM01 PO7936 (filed 15 Jul 1997)09/112,825 IJM02 PO7937 (filed 15 Jul 1997) 09/112,826 IJM03 PO8061(filed 15 Jul 1997) 09/112,827 IJM04 PO8054 (filed 15 Jul 1997)09/112,828 Publication date June 6, 2000 IJM05 PO8065 (filed 15 Jul1997) 6,071,750 IJM06 PO8055 (filed 15 Jul 1997) 09/113,108 IJM07 PO8053(filed 15 Jul 1997) 09/113,109 IJM08 PO8078 (filed 15 Jul 1997)09/113,123 IJM09 PO7933 (filed 15 Jul 1997) 09/113,114 IJM10 PO7950(filed 15 Jul 1997) 09/113,115 IJM11 PO7949 (filed 15 Jul 1997)09/113,129 IJM12 PO8060 (filed 15 Jul 1997) 09/113,124 IJM13 PO8059(filed 15 Jul 1997) 09/113,125 IJM14 PO8073 (filed 15 Jul 1997)09/113,126 IJM15 PO8076 (filed 15 Jul 1997) 09/113,119 IJM16 PO8075(filed 15 Jul 1997) 09/113,120 IJM17 PO8079 (filed 15 Jul 1997)09/113,221 IJM18 PO8050 (filed 15 Jul 1997) 09/113,116 IJM19 PO8052(filed 15 Jul 1997) 09/113,118 IJM20 PO7948 (filed 15 Jul 1997)09/113,117 IJM21 PO7951 (filed 15 Jul 1997) 09/113,113 IJM22 PO8074(filed 15 Jul 1997) 09/113,130 IJM23 PO7941 (filed 15 Jul 1997)09/113,110 IJM24 PO8077 (filed 15 Jul 1997) 09/113,112 IJM25 PO8058(filed 15 Jul 1997) 09/113,087 IJM26 PO8051 (filed 15 Jul 1997)09/113,074 IJM27 PO8045 (filed 15 Jul 1997) 6,111,754 Publication dateAugust 29, 2000 IJM28 PO7952 (filed 15 Jul 1997) 09/113,088 IJM29 PO8046(filed 15 Jul 1997) 09/112,771 IJM30 PO9390 (filed 23 Sep 1997)09/112,769 IJM31 PO9392 (filed 23 Sep 1997) 09/112,770 IJM32 PP0889(filed 12 Dec 1997) 09/112,798 IJM35 PP0887 (filed 12 Dec 1997)09/112,801 IJM36 PP0882 (filed 12 Dec 1997) 09/112,800 IJM37 PP0874(filed 12 Dec 1997) 09/112,799 IJM38 PP1396 (filed 19 Jan 1997)09/113,098 IJM39 PP3989 (filed 9 Jun 1998) 09/112,833 IJM40 PP2591(filed 24 Mar 1998) 09/112,832 IJM41 PP3990 (filed 9 Jun 1998)09/112,831 IJM42 PP3986 (filed 9 Jun 1998) 09/112,830 IJM43 PP3984(filed 9 Jun 1998) 09/112,836 IJM44 PP3982 (filed 9 Jun 1998) 09/112,835IJM45 PP0895 (filed 12 Dec 1997) 09/113,102 IR01 PP0870 (filed 12 Dec1997) 09/113,106 IR02 PP0869 (filed 12 Dec 1997) 09/113,105 IR04 PP0887(filed 12 Dec 1997) 09/113,104 IR05 PP0885 (filed 12 Dec 1997)09/112,810 IR06 PP0884 (filed 12 Dec 1997) 09/112,766 IR10 PP0886 (filed12 Dec 1997) 09/113,085 IR12 PP0871 (filed 12 Dec 1997) 09/113,086 IR13PP0876 (filed 12 Dec 1997) 09/113,094 IR14 PP0877 (filed 12 Dec 1997)09/122,760 IR16 PP0878 (filed 12 Dec 1997) 09/112,773 IR17 PP0879 (filed12 Dec 1997) 09/112,774 IR18 PP0883 (filed 12 Dec 1997) 09/112,775 IR19PP0880 (filed 12 Dec 1997) 09/112,795 Publication date November 28, IR202000 PP0881 (filed 12 Dec 1997) 09/113,092 IR21 PO8006 (filed 15 Jul1997) 6,087,638 Publication date July 11, 20000 MEMS02 PO8007 (filed 15Jul 1997) 09/113,093 MEMS03 PO8007 (filed 15 Jul 1997) 09/113,062 MEMS04PO8010 (filed 15 Jul 1997) 6,041,600 Publication date March 28, 2000MEMS05 PO8011 (filed 15 Jul 1997) 09/113,082 MEMS06 PO7947 (filed 15 Jul1997) 6,067,797 Publication date May 30, 20000 MEMS07 PO7944 (filed 15Jul 1997) 09/113,080 MEMS09 PO7946 (filed 15 Jul 1997) 6,044,646Publication date April 4, 2000 MEMS10 PO9393 (filed 23 Sep 1997)09/113,065 MEMS11 PP0875 (filed 12 Dec 1997) 09/113,078 MEMS12 PP0894(filed 12 Dec 1997) 09/113,075 MEMS13

STATEMENT REGARDING FEDERALLY SPONSORED RESEARCH OR DEVELOPMENT

Not applicable

FIELD OF THE INVENTION

The present invention relates to the provision of a printhead re-cappingmechanism for re-capping an inkjet printhead when the printhead is notis use.

BACKGROUND OF THE INVENTION

Recently, a handheld portable camera system has been proposed whichincorporates a “pagewidth” photo wide inkjet printhead for the printingof images on demand.

With any such system, it is highly likely that the camera will be leftfor extended periods of time in an unused state. Given the camera systemis proposed to have a pagewidth inkjet printhead, there is thesubstantial problem that, should the printhead be left unattended for asubstantial period of time, the ink will generally dry out. It wouldtherefore be desirable if a printhead capping mechanism was provided forthe capping of the printhead when not in use.

Further, as it is proposed utilising such a re-capping mechanism in adisposable handheld camera system, it will be desirable to provide foran extremely inexpensive form of re-capping mechanism that can beutilised in an inexpensive form of disposable camera.

SUMMARY OF THE INVENTION

It is an object of the present invention to provide for an inexpensiveform of printhead re-capping mechanism to be utilised in a handhelddisposable camera system or the like.

In accordance with a first aspect of the present invention, there isprovided a print head recapping mechanism for recapping a pagewidth inkjetting print head structure, comprising a first stationary ferrous arm;a solenoid coil wrapped around a portion of the ferrous arm; a secondmoveable arm located substantially adjacent the first arm and biasedtowards the printhead structure; a series of membranes attached to thesecond moveable arm the membranes sealing the print head structure whenin a rest position; the solenoid being activated to cause the moveablearm to move away from the surface of the print head structure sufficientto allow a “paper or film” to be inserted between the membranes and theprint head structure for the printing of ink thereon.

Preferably, the membranes are resiliently collapsible against thesurface of the print head structure. The membranes can comprise twomutually opposed elastomer strips running substantially the length ofthe ink jetting portions of the print head structure so as to surroundthe ink jetting portions.

The solenoid can include an elongated winding of a current carrying wirewhich is wrapped around a protruding portion of the first arm, theelongation being substantially the length of the print head structure.Further, the second movable arm is biased against the surface of theprint head structure. The solenoid can be activated to move the secondarm closely adjacent the first arm with a first level of current and thesolenoid is retained whilst printing closely adjacent the first arm witha second substantially lower level of current. The present invention hasparticular application in a hand held camera device.

BRIEF DESCRIPTION OF THE DRAWINGS

Notwithstanding any other forms which may fall within the scope of thepresent invention, preferred forms of the invention will now bedescribed, by way of example only, with reference to the accompanyingdrawings in which:

FIG. 1 illustrates a front perspective view of the assembled camera ofthe preferred embodiment;

FIG. 2 illustrates a rear perspective view, partly exploded, of thepreferred embodiment;

FIG. 3 is a perspective view of the chassis of the preferred embodiment;

FIG. 4 is a perspective view of the chassis illustrating mounting ofelectric motors;

FIG. 5 is an exploded perspective view of the ink supply mechanism ofthe preferred embodiment;

FIG. 6 is a rear perspective view of the assembled form of the inksupply mechanism of the preferred embodiment;

FIG. 7 is a front perspective view of the assembled form of the inksupply mechanism of the preferred embodiment;

FIG. 8 is an exploded perspective view of the platten unit of thepreferred embodiment;

FIG. 9 is a perspective view of the assembled form of the platten unit;

FIG. 10 is also a perspective view of the assembled form of the plattenunit;

FIG. 11 is an exploded perspective view of the printhead recappingmechanism of the preferred embodiment;

FIG. 12 is a close up exploded perspective view of the recappingmechanism of the preferred embodiment;

FIG. 13 is an exploded perspective view of the ink supply cartridge ofthe preferred embodiment;

FIG. 14 is a close up perspective view, partly in section, of theinternal portions of the ink supply cartridge in an assembled form;

FIG. 15 is a schematic block diagram of one form of chip layer of theimage capture and processing chip of the preferred embodiment;

FIG. 16 is an exploded perspective view illustrating the assemblyprocess of the preferred embodiment;

FIG. 17 illustrates a front exploded perspective view of the assemblyprocess of the preferred embodiment;

FIG. 18 illustrates a perspective view of the assembly process of thepreferred embodiment;

FIG. 19 illustrates a perspective view of the assembly process of thepreferred embodiment;

FIG. 20 is a perspective view illustrating the insertion of the plattenunit in the preferred embodiment;

FIG. 21 illustrates the interconnection of the electrical components ofthe preferred embodiment;

FIG. 22 illustrates the process of assembling the preferred embodiment;and

FIG. 23 is a perspective view further illustrating the assembly processof the preferred embodiment.

DESCRIPTION OF PREFERRED AND OTHER EMBODIMENTS

Turning initially simultaneously to FIG. 1 and FIG. 2 there areillustrated perspective views of an assembled camera constructed inaccordance with the preferred embodiment with FIG. 1 showing a frontperspective view and FIG. 2 showing a rear perspective view. The camera1 includes a paper or plastic film jacket 2 which can include simplifiedinstructions 3 for the operation of the camera system 1. The camerasystem 1 includes a first “take” button 4 which is depressed to capturean image. The captured image is output via output slot 6. A further copyof the image can be obtained through depressing a second “printer copy”button 7 whilst an LED light 5 is illuminated. The camera system alsoprovides the usual view finder 8 in addition to a CCD imagecapture/lensing system 9.

The camera system 1 provides for a standard number of output printsafter which the camera system 1 ceases to function. A prints leftindicator slot 10 is provided to indicate the number of remainingprints. A refund scheme at the point of purchase is assumed to beoperational for the return of used camera systems for recycling.

Turning now to FIG. 3, the assembly of the camera system is based aroundan internal chassis 12 which can be a plastic injection molded part. Apair of paper pinch rollers 28, 29 utilized for decurling are snapfitted into corresponding frame holes eg. 26, 27.

As shown in FIG. 4, the chassis 12 includes a series of mutually opposedprongs eg. 13, 14 into which is snapped fitted a series of electricmotors 16, 17. The electric motors 16, 17 can be entirely standard withthe motor 16 being of a stepper motor type. The motors 16, 17 includecogs 19, 20 for driving a series of gear wheels. A first set of gearwheels is provided for controlling a paper cutter mechanism and a secondset is provided for controlling print roll movement.

Turning next to FIGS. 5 to 7, there is illustrated an ink supplymechanism 40 utilized in the camera system. FIG. 5 illustrates a rearexploded perspective view, FIG. 6 illustrates a rear assembledperspective view and FIG. 7 illustrates a front assembled view. The inksupply mechanism 40 is based around an ink supply cartridge 42 whichcontains printer ink and a print head mechanism for printing outpictures on demand. The ink supply cartridge 42 includes a sidealuminium strip 43 which is provided as a shear strip to assist incutting images from a paper roll.

A dial mechanism 44 is provided for indicating the number of “printsleft”. The dial mechanism 44 is snap fitted through a correspondingmating portion 46 so as to be freely rotatable.

As shown in FIG. 6, the mechanism 40 includes a flexible PCB strip 47which interconnects with the print head and provides for control of theprint head. The interconnection between the Flex PCB strip and an imagesensor and print head chip can be via Tape Automated Bonding (TAB)strips 51, 58. A molded aspherical lens and aperture shim 50 (FIG. 5) isalso provided for imaging an image onto the surface of the image sensorchip normally located within cavity 53 and a light box module or hood 52is provided for snap fitting over the cavity 53 so as to provide forproper light control. A series of decoupling capacitors eg. 34 can alsobe provided. Further a plug 45 (FIG. 7) is provided for re-plugging inkholes after refilling. A series of guide prongs eg. 55-57 are furtherprovided for guiding the flexible PCB strip 47.

The ink supply mechanism 40 interacts with a platten unit 60 whichguides print media under a printhead located in the ink supplymechanism. FIG. 8 shows an exploded view of the platten unit 60, whileFIGS. 9 and 10 show assembled views of the platten unit. The plattenunit 60 includes a first pinch roller 61 which is snap fitted to oneside of a platten base 62. Attached to a second side of the platten base62 is a cutting mechanism 63 which traverses the platten unit 60 bymeans of a rod 64 having a screw thread which is rotated by means ofcogged wheel 65 which is also fitted to the platten base 62. The screwthreaded rod 64 mounts a block 67 which includes a cutting wheel 68fastened via a fastener 69. Also mounted to the block 67 is a counteractuator which includes a pawl 71. The pawl 71 acts to rotate the dialmechanism 44 of FIG. 6 upon the return traversal of the cutting wheel.As shown previously in FIG. 6, the dial mechanism 44 includes a coggedsurface which interacts with pawl 71, thereby maintaining a count of thenumber of photographs by means of numbers embossed on the surface ofdial mechanism 44. The cutting mechanism 63 is inserted into the plattenbase 62 by means of a snap fit via clips 74.

The platten unit 60 includes an internal recapping mechanism 80 forrecapping the print head when not in use. The recapping mechanism 80includes a sponge portion 81 and is operated via a solenoid coil so asto provide for recapping of the print head. In the preferred embodiment,there is provided an inexpensive form of printhead re-capping mechanismprovided for incorporation into a handheld camera system so as toprovide for printhead re-capping of an inkjet printhead.

FIG. 11 illustrates an exploded view of the recapping mechanism whilstFIG. 12 illustrates a close up of the end portion thereof. There-capping mechanism 80 is structured around a solenoid including a 16turn coil 75 which can comprise insulated wire. The coil 75 is turnedaround a first stationery solenoid arm 76 which is mounted on a bottomsurface of the platten base 62 (FIG. 8) and includes a post portion 77to magnify effectiveness of operation. The arm 76 can comprise a ferrousmaterial.

A second moveable arm 78 of the solenoid actuator is also provided. Thearm 78 is moveable and is also made of ferrous material. Mounted on thearm is a sponge portion surrounded by an elastomer strip 79. Theelastomer strip 79 is of a generally arcuate cross-section and act as aleaf spring against the surface of the printhead ink supply cartridge 42(FIG. 5) so as to provide for a seal against the surface of theprinthead ink supply cartridge 42. In the quiescent position anelastomer spring unit 87, 88 acts to resiliently deform the elastomerseal 79 against the surface of the ink supply unit 42.

When it is desired to operate the printhead unit, upon the insertion ofpaper, the solenoid coil 75 is activated so as to cause the arm 78 tomove down to be adjacent to the end plate 76. The arm 78 is held againstend plate 76 while the printhead is printing by means of a small “keepercurrent” in coil 75. Simulation results indicate that the keeper currentcan be significantly less than the actuation current. Subsequently,after photo printing, the paper is guillotined by the cutting mechanism63 of FIG. 8 acting against Aluminium Strip 43, and rewound so as toclear the area of the re-capping mechanism 80. Subsequently, the currentis turned off and springs 87, 88 return the arm 78 so that the elastomerseal is again resting against the printhead ink supply cartridge.

It can be seen that the preferred embodiment provides for a simple andinexpensive means of re-capping a printhead through the utilisation of asolenoid type device having a long rectangular form. Further, thepreferred embodiment utilises minimal power in that currents are onlyrequired whilst the device is operational and additionally, only a lowkeeper current is required whilst the printhead is printing.

Turning next to FIG. 13 and 14, FIG. 13 illustrates an explodedperspective of the ink supply cartridge 42 whilst FIG. 14 illustrates aclose up sectional view of a bottom of the ink supply cartridge with theprinthead unit in place. The ink supply cartridge 42 is based around apagewidth printhead 102 which comprises a long slither of silicon havinga series of holes etched on the back surface for the supply of ink to afront surface of the silicon wafer for subsequent ejection via a microelectro mechanical system. The form of ejection can be many differentforms such as those set out in the tables below.

Of course, many other inkjet technologies, as referred to the attachedtables below, can also be utilised when constructing a printhead unit102. The fundamental requirement of the ink supply cartridge 42 is thesupply of ink to a series of color channels etched through the backsurface of the printhead 102. In the description of the preferredembodiment, it is assumed that a three color printing process is to beutilised so as to provide full color picture output. Hence, the printsupply unit includes three ink supply reservoirs being a cyan reservoir104, a magenta reservoir 105 and a yellow reservoir 106. Each of thesereservoirs is required to store ink and includes a corresponding spongetype material 107-109 which assists in stabilising ink within thecorresponding ink channel and inhibiting the ink from sloshing back andforth when the printhead is utilised in a handheld camera system. Thereservoirs 104, 105, 106 are formed through the mating of first exteriorplastic piece 110 and a second base piece 111.

At a first end 118 of the base piece 111 a series of air inlet 113-115are provided. Each air inlet leads to a corresponding winding channelwhich is hydrophobically treated so as to act as an ink repellent andtherefore repel any ink that may flow along the air inlet channel. Theair inlet channel further takes a convoluted path assisting in resistingany ink flow out of the chambers 104-106. An adhesive tape portion 117is provided for sealing the channels within end portion 118.

At the top end, there is included a series of refill holes (not shown)for refilling corresponding ink supply chambers 104, 105, 106. A plug121 is provided for sealing the refill holes.

Turning now to FIG. 14, there is illustrated a close up perspectiveview, partly in section through the ink supply cartridge 42 of FIG. 13when formed as a unit. The ink supply cartridge includes the three colorink reservoirs 104, 105, 106 which supply ink to different portions ofthe back surface of printhead 102 which includes a series of apertures128 defined therein for carriage of the ink to the front surface.

The ink supply cartridge 42 includes two guide walls 124, 125 whichseparate the various ink chambers and are tapered into an end portionabutting the surface of the printhead 102. The guide walls 124, 125 arefurther mechanically supported by block portions eg. 126 which areplaced at regular intervals along the length of the ink supply unit. Theblock portions 126 leave space at portions close to the back ofprinthead 102 for the flow of ink around the back surface thereof.

The ink supply unit is preferably formed from a multi-part plasticinjection mold and the mold pieces eg. 110, 111 (FIG. 13) snap togetheraround the sponge pieces 107, 109. Subsequently, a syringe type devicecan be inserted in the ink refill holes and the ink reservoirs filledwith ink with the air flowing out of the air outlets 113-115.Subsequently, the adhesive tape portion 117 and plug 121 are attachedand the printhead tested for operation capabilities. Subsequently, theink supply cartridge 42 can be readily removed for refilling by means ofremoving the ink supply cartridge, performing a washing cycle, and thenutilising the holes for the insertion of a refill syringe filled withink for refilling the ink chamber before returning the ink supplycartridge 42 to a camera.

Turning now to FIG. 15, there is shown an example layout of the ImageCapture and Processing Chip (ICP) 48.

The Image Capture and Processing Chip 48 provides most of the electronicfunctionality of the camera with the exception of the print head chip.The chip 48 is a highly integrated system. It combines CMOS imagesensing, analog to digital conversion, digital image processing, DRAMstorage, ROM, and miscellaneous control functions in a single chip.

The chip is estimated to be around 32 mm² using a leading edge 0.18micron CMOS/DRAM/APS process. The chip size and cost can scale somewhatwith Moore's law, but is dominated by a CMOS active pixel sensor array201, so scaling is limited as the sensor pixels approach the diffractionlimit.

The ICP 48 includes CMOS logic, a CMOS image sensor, DRAM, and analogcircuitry. A very small amount of flash memory or other non-volatilememory is also preferably included for protection against reverseengineering.

Alternatively, the ICP can readily be divided into two chips: one forthe CMOS imaging array, and the other for the remaining circuitry. Thecost of this two chip solution should not be significantly differentthan the single chip ICP, as the extra cost of packaging and bond-padarea is somewhat cancelled by the reduced total wafer area requiring thecolor filter fabrication steps. The ICP preferably contains thefollowing functions:

Function 1.5 megapixel image sensor Analog Signal Processors Imagesensor column decoders Image sensor row decoders Analogue to DigitalConversion (ADC) Column ADC's Auto exposure 12 Mbits of DRAM DRAMAddress Generator Color interpolator Convolver Color ALU Halftone matrixROM Digital halftoning Print head interface 8 bit CPU core Program ROMFlash memory Scratchpad SRAM Parallel interface (8 bit) Motor drivetransistors (5) Clock PLL JTAG test interface Test circuits Busses Bondpads

The CPU, DRAM, Image sensor, ROM, Flash memory, Parallel interface, JTAGinterface and ADC can be vendor supplied cores. The ICP is intended torun on 1.5 V to minimize power consumption and allow convenientoperation from two AA type battery cells.

FIG. 15 illustrates a layout of the ICP 48. The ICP 48 is dominated bythe imaging array 201, which consumes around 80% of the chip area. Theimaging array is a CMOS 4 transistor active pixel design with aresolution of 1,500×1,000. The array can be divided into theconventional configuration, with two green pixels, one red pixel, andone blue pixel in each pixel group. There are 750×500 pixel groups inthe imaging array.

The latest advances in the field of image sensing and CMOS image sensingin particular can be found in the October, 1997 issue of IEEETransactions on Electron Devices and, in particular, pages 1689 to 1968.Further, a specific implementation similar to that disclosed in thepresent application is disclosed in Wong et. al, “CMOS Active PixelImage Sensors Fabricated Using a 1.8 V, 0.25 μm CMOS Technology”, IEDM1996, page 915

The imaging array uses a 4 transistor active pixel design of a standardconfiguration. To minimize chip area and therefore cost, the imagesensor pixels should be as small as feasible with the technologyavailable. With a four transistor cell, the typical pixel size scales as20 times the lithographic feature size. This allows a minimum pixel areaof around 3.6 μm×3.6 μm. However, the photosite must be substantiallyabove the diffraction limit of the lens. It is also advantageous to havea square photosite, to maximize the margin over the diffraction limit inboth horizontal and vertical directions. In this case, the photosite canbe specified as 2.5 μm×2.5 μm. The photosite can be a photogate, pinnedphotodiode, charge modulation device, or other sensor.

The four transistors are packed as an ‘L’ shape, rather than arectangular region, to allow both the pixel and the photosite to besquare. This reduces the transistor packing density slightly, increasingpixel size. However, the advantage in avoiding the diffraction limit isgreater than the small decrease in packing density.

The transistors also have a gate length which is longer than the minimumfor the process technology. These have been increased from a drawnlength of 0.18 micron to a drawn length of 0.36 micron. This is toimprove the transistor matching by making the variations in gate lengthrepresent a smaller proportion of the total gate length.

The extra gate length, and the ‘L’ shaped packing, mean that thetransistors use more area than the minimum for the technology. Normally,around 8 μm² would be required for rectangular packing. Preferably, 9.75μm² has been allowed for the transistors.

The total area for each pixel is 16 μm², resulting from a pixel size of4 μm×4 μm. With a resolution of 1,500×1,000, the area of the imagingarray 101 is 6,000 μm×4,000 μm, or 24 mm².

The presence of a color image sensor on the chip affects the processrequired in two major ways:

The CMOS fabrication process should be optimized to minimize darkcurrent

Color filters are required. These can be fabricated using dyedphotosensitive polyimides, resulting in an added process complexity ofthree spin coatings, three photolithographic steps, three developmentsteps, and three hardbakes.

There are 15,000 analog signal processors (ASPs) 205, one for each ofthe columns of the sensor. The ASPs amplify the signal, provide a darkcurrent reference, sample and hold the signal, and suppress the fixedpattern noise (FPN).

There are 375 analog to digital converters 206, one for each fourcolumns of the sensor array. These may be delta-sigma or successiveapproximation type ADC's. A row of low column ADC's are used to reducethe conversion speed required, and the amount of analog signaldegradation incurred before the signal is converted to digital. Thisalso eliminates the hot spot (affecting local dark current) and thesubstrate coupled noise that would occur if a single high speed ADC wasused. Each ADC also has two four bit DAC's which trim the offset andscale of the ADC to further reduce FPN variations between columns. TheseDAC's are controlled by data stored in flash memory during chip testing.

The column select logic 204 is a 1:1500 decoder which enables theappropriate digital output of the ADCs onto the output bus. As each ADCis shared by four columns, the least significant two bits of the rowselect control 4 input analog multiplexors.

A row decoder 207 is a 1:1000 decoder which enables the appropriate rowof the active pixel sensor array. This selects which of the 1000 rows ofthe imaging array is connected to analog signal processors. As the rowsare always accessed in sequence, the row select logic can be implementedas a shift register.

An auto exposure system 208 adjusts the reference voltage of the ADC 205in response to the maximum intensity sensed during the previous frameperiod. Data from the green pixels is passed through a digital peakdetector. The peak value of the image frame period before capture (thereference frame) is provided to a digital to analogue converter(DAC),which generates the global reference voltage for the column ADCs. Thepeak detector is reset at the beginning of the reference frame. Theminimum and maximum values of the three RGB color components are alsocollected for color correction.

The second largest section of the chip is consumed by a DRAM 210 used tohold the image. To store the 1,500×1,000 image from the sensor withoutcompression, 1.5 Mbytes of DRAM 210 are required. This equals 12 Mbits,or slightly less than 5% of a 256 Mbit DRAM. The DRAM technology assumedis of the 256 Mbit generation implemented using 0.18 μm CMOS.

Using a standard 8F cell, the area taken by the memory array is 3.11mm². When row decoders, column sensors, redundancy, and other factorsare taken into account, the DRAM requires around 4 mm².

This DRAM 210 can be mostly eliminated if analog storage of the imagesignal can be accurately maintained in the CMOS imaging array for thetwo seconds required to print the photo. However, digital storage of theimage is preferable as it is maintained without degradation, isinsensitive to noise, and allows copies of the photo to be printedconsiderably later.

A DRAM address generator 211 provides the write and read addresses tothe DRAM 210. Under normal operation, the write address is determined bythe order of the data read from the CMOS image sensor 201. This willtypically be a simple raster format. However, the data can be read fromthe sensor 201 in any order, if matching write addresses to the DRAM aregenerated. The read order from the DRAM 210 will normally simply matchthe requirements of a color interpolator and the print head. As thecyan, magenta, and yellow rows of the print head are necessarily offsetby a few pixels to allow space for nozzle actuators, the colors are notread from the DRAM simultaneously. However, there is plenty of time toread all of the data from the DRAM many times during the printingprocess. This capability is used to eliminate the need for FIFOs in theprint head interface, thereby saving chip area. All three RGB imagecomponents can be read from the DRAM each time color data is required.This allows a color space converter to provide a more sophisticatedconversion than a simple linear RGB to CMY conversion.

Also, to allow two dimensional filtering of the image data withoutrequiring line buffers, data is re-read from the DRAM array.

The address generator may also implement image effects in certain modelsof camera. For example, passport photos are generated by a manipulationof the read addresses to the DRAM. Also, image framing effects (wherethe central image is reduced), image warps, and kaleidoscopic effectscan all be generated by manipulating the read addresses of the DRAM.

While the address generator 211 may be implemented with substantialcomplexity if effects are built into the standard chip, the chip arearequired for the address generator is small, as it consists only ofaddress counters and a moderate amount of random logic.

A color interpolator 214 converts the interleaved pattern of red,2×green, and blue pixels into RGB pixels. It consists of three 8 bitadders and associated registers. The divisions are by either 2 (forgreen) or 4 (for red and blue) so they can be implemented as fixedshifts in the output connections of the adders.

A convolver 215 is provided as a sharpening filter which applies a smallconvolution kernel (5 ×5) to the red, green, and blue planes of theimage. The convolution kernel for the green plane is different from thatof the red and blue planes, as green has twice as many samples. Thesharpening filter has five functions:

To improve the color interpolation from the linear interpolationprovided by the color interpolator, to a close approximation of a sincinterpolation.

To compensate for the image ‘softening’ which occurs duringdigitization.

To adjust the image sharpness to match average consumer preferences,which are typically for the image to be slightly sharper than reality.As the single use camera is intended as a consumer product, and not aprofessional photographic products, the processing can match the mostpopular settings, rather than the most accurate.

To suppress the sharpening of high frequency (individual pixel) noise.The function is similar to the ‘unsharp mask’ process.

To antialias Image Warping.

These functions are all combined into a single convolution matrix. Asthe pixel rate is low (less than 1 Mpixel per second) the total numberof multiplies required for the three color channels is 56 millionmultiplies per second. This can be provided by a single multiplier.Fifty bytes of coefficient ROM are also required.

A color ALU 113 combines the functions of color compensation and colorspace conversion into the one matrix multiplication, which is applied toevery pixel of the frame. As with sharpening, the color correctionshould match the most popular settings, rather than the most accurate.

A color compensation circuit of the color ALU provides compensation forthe lighting of the photo. The vast majority of photographs aresubstantially improved by a simple color compensation, whichindependently normalizes the contrast and brightness of the three colorcomponents.

A color look-up table (CLUT) 212 is provided for each color component.These are three separate 256×8 SRAMs, requiring a total of 6,144 bits.The CLUTs are used as part of the color correction process. They arealso used for color special effects, such as stochastically selected“wild color” effects.

A color space conversion system of the color ALU converts from the RGBcolor space of the image sensor to the CMY color space of the printer.The simplest conversion is a 1's complement of the RGB data. However,this simple conversion assumes perfect linearity of both color spaces,and perfect dye spectra for both the color filters of the image sensor,and the ink dyes. At the other extreme is a tri-linear interpolation ofa sampled three dimensional arbitrary transform table. This caneffectively match any non-linearity or differences in either colorspace. Such a system is usually necessary to obtain good color spaceconversion when the print engine is a color electrophotographic However,since the non-linearity of a halftoned ink jet output is very small, asimpler system can be used. A simple matrix multiply can provideexcellent results. This requires nine multiplies and six additions percontone pixel. However, since the contone pixel rate is low (less than 1Mpixel/sec) these operations can share a single multiplier and adder.The multiplier and adder are used in a color ALU which is shared withthe color compensation function.

Digital halftoning can be performed as a dispersed dot ordered ditherusing a stochastic optimized dither cell. A halftone matrix ROM 216 isprovided for storing dither cell coefficients. A dither cell size of32×32 is adequate to ensure that the cell repeat cycle is not visible.The three colors—cyan, magenta, and yellow—are all dithered using thesame cell, to ensure maximum co-positioning of the ink dots. Thisminimizes ‘muddying’ of the mid-tones which results from bleed of dyesfrom one dot to adjacent dots while still wet. The total ROM sizerequired is 1 KByte, as the one ROM is shared by the halftoning unitsfor each of the three colors.

The digital halftoning used is dispersed dot ordered dither withstochastic optimized dither matrix. While dithering does not produce animage quite as ‘sharp’ as error diffusion, it does produce a moreaccurate image with fewer artifacts. The image sharpening produced byerror diffusion is artificial, and less controllable and accurate than‘unsharp mask’ filtering performed in the contone domain. The high printresolution (1,600 dpi×1,600 dpi) results in excellent quality when usinga well formed stochastic dither matrix.

Digital halftoning is performed by a digital halftoning unit 217 using asimple comparison between the contone information from the DRAM 210 andthe contents of the dither matrix 216. During the halftone process, theresolution of the image is changed from the 250 dpi of the capturedcontone image to the 1,600 dpi of the printed image. Each contone pixelis converted to an average of 40.96 halftone dots.

The ICP incorporates a 16 bit microcontroller CPU core 219 to run themiscellaneous camera functions, such as reading the buttons, controllingthe motor and solenoids, setting up the hardware, and authenticating therefill station. The processing power required by the CPU is very modest,and a wide variety of processor cores can be used. As the entire CPUprogram is run from a small ROM 220, program compatibility betweencamera versions is not important, as no external programs are run. A 2Mbit (256 Kbyte) program and data ROM 220 is included on chip. Most ofthis ROM space is allocated to data for outline graphics and fonts forspecialty cameras. The program requirements are minor. The single mostcomplex task is the encrypted authentication of the refill station. TheROM requires a single transistor per bit.

A Flash memory 221 may be used to store a 128 bit authentication code.This provides higher security than storage of the authentication code inROM, as reverse engineering can be made essentially impossible. TheFlash memory is completely covered by third level metal, making the dataimpossible to extract using scanning probe microscopes or electronbeams. The authentication code is stored in the chip when manufactured.At least two other Flash bits are required for the authenticationprocess: a bit which locks out reprogramming of the authentication code,and a bit which indicates that the camera has been refilled by anauthenticated refill station. The flash memory can also be used to storeFPN correction data for the imaging array. Additionally, a phase lockedloop rescaling parameter is stored for scaling the clocking cycle to anappropriate correct time. The clock frequency does not require crystalaccuracy since no date functions are provided. To eliminate the cost ofa crystal, an on chip oscillator with a phase locked loop 224 is used.As the frequency of an on-chip oscillator is highly variable from chipto chip, the frequency ratio of the oscillator to the PLL is digitallytrimmed during initial testing. The value is stored in Flash memory 221.This allows the clock PLL to control the ink-jet heater pulse width withsufficient accuracy.

A scratchpad SRAM is a small static RAM 222 with a 6T cell. Thescratchpad provided temporary memory for the 16 bit CPU. 1024 bytes isadequate.

A print head interface 223 formats the data correctly for the printhead. The print head interface also provides all of the timing signalsrequired by the print head. These timing signals may vary depending upontemperature, the number of dots printed simultaneously, the print mediumin the print roll, and the dye density of the ink in the print roll.

The following is a table of external connections to the print headinterface:

Connection Function Pins DataBits[0-7] Independent serial data to theeight segments 8 of the print head BitClock Main data clock for theprint head 1 ColorEnable[0-2] Independent enable signals for the CMY 3actuators, allowing different pulse times for each color.BankEnable[0-1] Allows either simultaneous or interleaved 2 actuation oftwo banks of nozzles. This allows two different print speed/ powerconsumption tradeoffs NozzleSelect[0-4] Selects one of 32 banks ofnozzles for 5 simultaneous actuation ParallelXferClock Loads theparallel transfer register with the 1 data from the shift registersTotal 20

The print head utilized is composed of eight identical segments, each1.25 cm long. There is no connection between the segments on the printhead chip. Any connections required are made in the external TAB bondingfilm, which is double sided. The division into eight identical segmentsis to simplify lithography using wafer steppers. The segment width of1.25 cm fits easily into a stepper field. As the print head chip is longand narrow (10 cm×0.3 mm), the stepper field contains a single segmentof 32 print head chips. The stepper field is therefore 1.25 cm×1.6 cm.An average of four complete print heads are patterned in each waferstep.

A single BitClock output line connects to all 8 segments on the printhead. The 8 DataBits lines lead one to each segment, and are clockedinto the 8 segments on the print head simultaneously (on a BitClockpulse). For example, dot 0 is transferred to segment₀, dot 750 istransferred to segment₁, dot 1500 to segment₂ etc simultaneously.

The ParallelXferClock is connected to each of the 8 segments on theprint head, so that on a single pulse, all segments transfer their bitsat the same time.

The NozzleSelect, BankEnable and ColorEnable lines are connected to eachof the 8 segments, allowing the print head interface to independentlycontrol the duration of the cyan, magenta, and yellow nozzle energizingpulses. Registers in the Print Head Interface allow the accuratespecification of the pulse duration between 0 and 6 ms, with a typicalduration of 2 ms to 3 ms.

A parallel interface 125 connects the ICP to individual staticelectrical signals. The CPU is able to control each of these connectionsas memory mapped I/O via a low speed bus.

The following is a table of connections to the parallel interface:

Connection Direction Pins Paper transport stepper motor Output 4 Cappingsolenoid Output 1 Copy LED Output 1 Photo button Input 1 Copy buttonInput 1 Total 8

Seven high current drive transistors eg. 227 are required. Four are forthe four phases of the main stepper motor, two are for the guillotinemotor, and the remaining transistor is to drive the capping solenoid.These transistors are allocated 20,000 square microns (600,000 F) each.As the transistors are driving highly inductive loads, they must eitherbe turned off slowly, or be provided with a high level of back EMFprotection. If adequate back EMF protection cannot be provided using thechip process chosen, then external discrete transistors should be used.The transistors are never driven at the same time as the image sensor isused. This is to avoid voltage fluctuations and hot spots affecting theimage quality. Further, the transistors are located as far away from thesensor as possible.

A standard JTAG (Joint Test Action Group) interface 228 is included inthe ICP for testing purposes and for interrogation by the refillstation. Due to the complexity of the chip, a variety of testingtechniques are required, including BIST (Built In Self Test) andfunctional block isolation. An overhead of 10% in chip area is assumedfor chip testing circuitry for the random logic portions. The overheadfor the large arrays the image sensor and the DRAM is smaller.

The JTAG interface is also used for authentication of the refillstation. This is included to ensure that the cameras are only refilledwith quality paper and ink at a properly constructed refill station,thus preventing inferior quality refills from occurring. The camera mustauthenticate the refill station, rather than vice versa. The secureprotocol is communicated to the refill station during the automated testprocedure. Contact is made to four gold plated spots on the ICP/printhead TAB by the refill station as the new ink is injected into the printhead.

FIG. 16 illustrates a rear view of the next step in the constructionprocess whilst FIG. 17 illustrates a front view.

Turning now to FIG. 16, the assembly of the camera system proceeds viafirst assembling the ink supply mechanism 40. The flex PCB isinterconnected with batteries 84 only one of which is shown, which areinserted in the middle portion of a print roll 85 which is wrappedaround a plastic former 86. An end cap 89 is provided at the other endof the print roll 85 so as to fasten the print roll and batteries firmlyto the ink supply mechanism.

The solenoid coil is interconnected (not shown) to interconnects 97, 98(FIG. 8) which include leaf spring ends for interconnection withelectrical contacts on the Flex PCB so as to provide for electricalcontrol of the solenoid.

Turning now to FIGS. 17-19 the next step in the construction process isthe insertion of the relevant gear trains into the side of the camerachassis. FIG. 17 illustrates a front view, FIG. 18 illustrates a rearview and FIG. 19 also illustrates a rear view. The first gear traincomprising gear wheels 22, 23 is utilised for driving the guillotineblade with the gear wheel 23 engaging the gear wheel 65 of FIG. 8. Thesecond gear train comprising gear wheels 24, 25 and 26 engage one end ofthe print roller 61 of FIG. 8. As best indicated in FIG. 18, the gearwheels mate with corresponding pins on the surface of the chassis withthe gear wheel 26 being snap fitted into corresponding mating hole 27.

Next, as illustrated in FIG. 20, the assembled platten unit 60 is theninserted between the print roll 85 and aluminium cutting blade 43.

Turning now to FIG. 21, by way of illumination, there is illustrated theelectrically interactive components of the camera system. As notedpreviously, the components are based around a Flex PCB board and includea TAB film 58 which interconnects the printhead 102 with the imagesensor and processing chip 48. Power is supplied by two AA typebatteries 83, 84 and a paper drive stepper motor 16 is provided inaddition to a rotary guillotine motor 17.

An optical element 31 is provided for snapping into a top portion of thechassis 12. The optical element 31 includes portions defining an opticalview finder 32, 33 which are slotted into mating portions 35, 36 in viewfinder channel 37. Also provided in the optical element 31 is a lensingsystem 38 for magnification of the prints left number in addition to anoptical pipe element 39 for piping light from the LED 5 for externaldisplay.

Turning next to FIG. 22, the assembled unit 90 is then inserted into afront outer case 91 which includes button 4 for activation of printouts.

Turning now to FIG. 23, next, the unit 90 is provided with a snap-onback cover 93 which includes a slot 6 and copy print button 7. A wrapperlabel containing instructions and advertising (not shown) is thenwrapped around the outer surface of the camera system and pinch clampedto the cover by means of clamp strip 96 which can comprise a flexibleplastic or rubber strip.

Subsequently, the preferred embodiment is ready for use as a one timeuse camera system that provides for instant output images on demand. Itwill be evident that the preferred embodiment further provides for arefillable camera system. A used camera can be collected and its outerplastic cases removed and recycled. A new paper roll and batteries canbe added and the ink cartridge refilled. A series of automatic testroutines can then be carried out to ensure that the printer is properlyoperational. Further, in order to ensure only authorised refills areconducted so as to enhance quality, routines in the on-chip program ROMcan be executed such that the camera authenticates the refilling stationusing a secure protocol. Upon authentication, the camera can reset aninternal paper count and an external case can be fitted on the camerasystem with a new outer label. Subsequent packing and shipping can thentake place.

It will be further readily evident to those skilled in the art that theprogram ROM can be modified so as to allow for a variety of digitalprocessing routines. In addition to the digitally enhanced photographsoptimised for mainstream consumer preferences, various other models canreadily be provided through mere re-programming of the program ROM. Forexample, a sepia classic old fashion style output can be providedthrough a remapping of the color mapping function. A further alternativeis to provide for black and white outputs again through a suitable colorremapping algorithm. Minimum color can also be provided to add a touchof color to black and white prints to produce the effect that wastraditionally used to colorize black and white photos. Further, passportphoto output can be provided through suitable address remappings withinthe address generators. Further, edge filters can be utilised as isknown in the field of image processing to produce sketched art styles.Further, classic wedding borders and designs can be placed around anoutput image in addition to the provision of relevant clip arts. Forexample, a wedding style camera might be provided. Further, a panoramicmode can be provided so as to output the well known panoramic format ofimages. Further, a postcard style output can be provided through theprinting of postcards including postage on the back of a print rollsurface. Further, cliparts can be provided for special events such asHalloween, Christmas etc. Further, kaleidoscopic effects can be providedthrough address remappings and wild color effects can be providedthrough remapping of the color lookup table. Many other forms of specialevent cameras can be provided for example, cameras dedicated to theOlympics, movie tie-ins, advertising and other special events.

The operational mode of the camera can be programmed so that upon thedepressing of the take photo a first image is sampled by the sensorarray to determine irrelevant parameters. Next a second image is againcaptured which is utilised for the output. The captured image is thenmanipulated in accordance with any special requirements before beinginitially output on the paper roll. The LED light is then activated fora predetermined time during which the DRAM is refreshed so as to retainthe image. If the print copy button is depressed during thispredetermined time interval, a further copy of the photo is output.After the predetermined time interval where no use of the camera hasoccurred, the onboard CPU shuts down all power to the camera systemuntil such time as the take button is again activated. In this way,substantial power savings can be realized.

Ink Jet Technologies

The embodiments of the invention use an ink jet printer type device. Ofcourse many different devices could be used. However presently popularink jet printing technologies are unlikely to be suitable.

The most significant problem with thermal ink jet is power consumption.This is approximately 100 times that required for high speed, and stemsfrom the energy-inefficient means of drop ejection. This involves therapid boiling of water to produce a vapor bubble which expels the ink.Water has a very high heat capacity, and must be superheated in thermalink jet applications. This leads to an efficiency of around 0.02%, fromelectricity input to drop momentum (and increased surface area) out.

The most significant problem with piezoelectric ink jet is size andcost. Piezoelectric crystals have a very small deflection at reasonabledrive voltages, and therefore require a large area for each nozzle.Also, each piezoelectric actuator must be connected to its drive circuiton a separate substrate. This is not a significant problem at thecurrent limit of around 300 nozzles per printhead, but is a majorimpediment to the fabrication of pagewidth printheads with 19,200nozzles.

Ideally, the ink jet technologies used meet the stringent requirementsof in-camera digital color printing and other high quality, high speed,low cost printing applications. To meet the requirements of digitalphotography, new ink jet technologies have been created. The targetfeatures include:

low power (less than 10 Watts)

high resolution capability (1,600 dpi or more)

photographic quality output

low manufacturing cost

small size (pagewidth times minimum cross section)

high speed (<2 seconds per page).

All of these features can be met or exceeded by the ink jet systemsdescribed below with differing levels of difficulty. Forty-fivedifferent ink jet technologies have been developed by the Assignee togive a wide range of choices for high volume manufacture. Thesetechnologies form part of separate applications assigned to the presentAssignee as set out in the table below under the heading CrossReferences to Related Applications.

The ink jet designs shown here are suitable for a wide range of digitalprinting systems, from battery powered one-time use digital cameras,through to desktop and network printers, and through to conmmercialprinting systems.

For ease of manufacture using standard process equipment, the printheadis designed to be a monolithic 0.5 micron CMOS chip with MEMS postprocessing. For color photographic applications, the printhead is 100 mmlong, with a width which depends upon the ink jet type. The smallestprinthead designed is IJ38, which is 0.35 mm wide, giving a chip area of35 square mm. The printheads each contain 19,200 nozzles plus data andcontrol circuitry.

Ink is supplied to the back of the printhead by injection molded plasticink channels. The molding requires 50 micron features, which can becreated using a lithographically micromachined insert in a standardinjection molding tool. Ink flows through holes etched through the waferto the nozzle chambers fabricated on the front surface of the wafer. Theprinthead is connected to the camera circuitry by tape automatedbonding.

Tables of Drop-on-Demand Ink Jets

Eleven important characteristics of the fundamental operation ofindividual ink jet nozzles have been identified. These characteristicsare largely orthogonal, and so can be elucidated as an elevendimensional matrix. Most of the eleven axes of this matrix includeentries developed by the present assignee.

The following tables form the axes of an eleven dimensional table of inkjet types.

Actuator mechanism (18 types)

Basic operation mode (7 types)

Auxiliary mechanism (8 types)

Actuator amplification or modification method (17 types)

Actuator motion (19 types)

Nozzle refill method (4 types)

Method of restricting back-flow through inlet (10 types)

Nozzle clearing method (9 types)

Nozzle plate construction (9 types)

Drop ejection direction (5 types)

Ink type (7 types)

The complete eleven dimensional table represented by these axes contains36.9 billion possible configurations of ink jet nozzle. While not all ofthe possible combinations result in a viable ink jet technology, manymillion configurations are viable. It is clearly impractical toelucidate all of the possible configurations. Instead, certain ink jettypes have been investigated in detail. These are designated IJ01 toIJ45 above which match the docket numbers in the table under the headingCross References to Related Applications.

Other ink jet configurations can readily be derived from theseforty-five examples by substituting alternative configurations along oneor more of the 11 axes. Most of the IJ01 to IJ45 examples can be madeinto ink jet printheads with characteristics superior to any currentlyavailable ink jet technology.

Where there are prior art examples known to the inventor, one or more ofthese examples are listed in the examples column of the tables below.The IJ01 to IJ45 series are also listed in the examples column. In somecases, a print technology may be listed more than once in a table, whereit shares characteristics with more than one entry.

Suitable applications for the ink jet technologies include: Homeprinters, Office network printers, Short run digital printers,Commercial print systems, Fabric printers, Pocket printers, Internet WWWprinters, Video printers, Medical imaging, Wide format printers,Notebook PC printers, Fax machines, Industrial printing systems,Photocopiers, Photographic minilabs etc.

The information associated with the aforementioned 11 dimensional matrixare set out in the following tables.

Description Advantages Disadvantages Examples ACTUATOR MECHANISM(APPLIED ONLY TO SELECTED INK DROPS) Thermal An electrothermal Largeforce High power Canon Bubblejet bubble heater heats the ink togenerated Ink carrier 1979 Endo et al GB above boiling point, Simplelimited to water patent 2,007,162 transferring significant constructiowLow efficiency Xerox heater-in- heat to the aqueous No moving parts Highpit 1990 Hawkins et ink. A bubble Fast operation temperatures al U.S.Pat. No. 4,899,181 nucleates and quickly Small chip area requiredHewlett-Packard forms, expelling the required for actuator Highmechanical TIJ 1982 Vaught et ink. stress al U.S. Pat. No. 4,490,728 Theefflciency of the Unusual process is low, with materials requiredtypically less than Large drive 0.05% of the electrical transistorsenergy being Cavitation causes transformed into actuator failure kineticenergy of the Kogation reduces drop. bubble formation Large print headsare difficult to fabricate Piezo- A piezoelectric crystal Low power Verylarge area Kyser et al U.S. Pat. No. electric such as lead consumptionrequired for actuator 3,946,398 lanthanum zirconate Many ink typesDifficult to Zoltan U.S. Pat. No. (PZT) is electrically can be usedintegrate with 3,683,212 activated, and either Fast operationelectronics 1973 Stemme expands, shears, or High efficiency High voltageU.S. Pat. No. 3,747,120 bends to apply drive transistors Epson Styluspressure to the ink, required Tektronix ejecting drops. Full pagewidthIJ04 print beads impractical due to actuator size Requires electricalpoling in high field strengths during manufacture Electro- An electricfield is Low power Low maximum Seiko Epson, strictive used to activateconsumption strain (approx. Usui et all JP electrostriction in Many inktypes 0.01%) 253401/96 relaxor materials such can be used Large areaIJ04 as lead lanthanum Low thermal required for actuator zirconatetitanate expansion due to low strain (PLZT) or lead Electric fieldResponse speed magnesium niobate strength required is marginal (˜10(PMN). (approx. 3.5 V/μm) μs) can be generated High voltage withoutdifficulty drive transistors Does not require required electrical polingFull pagewidth print heads impractical due to actuator size Ferro- Anelectric field is Low power Difficult to IJ04 electric used to induce aphase consumption integrate with transition between the Many ink typeselectronics antiferroelectric (AFE) can be used Unusual andferroelectric (FE) Fast operation materials such as phase. Perovskite(<1 μs) PLZSnT are materials such as tin Relatively high requiredmodified lead longitudinal strain Actuators require lanthanum zirconateHigh efficiency a large area titanate (PLZSnT) Electric field exhibitlarge strains of strength of around 3 up to 1% associated V/μm can bereadily with the AFE to FE provided phase transition. Electro-Conductive plates are Low power Difficult to IJ02, IJ04 static platesseparated by a consumption operate electrostatic compressible or fluidMany ink types devices in an dielectric (usually air). can be usedaqueous Upon application of a Fast operation environment voltage, theplates The electrostatic attract each other and actuator will displaceink, causing normally need to be drop ejection. The separated from theconductive plates may ink be in a comb or Very large area honeycombstructure, required to achieve or stacked to increase high forces thesurface area and High voltage therefore the force. drive transistors maybe required Full pagewidth print heads are not competitive due toactuator size Electro- A strong electric field Low current High voltage1989 Saito et al, static pull is applied to tbe ink, consumptionrequired U.S. Pat. No. 4,799,068 on ink whereupon Low temperature May bedamaged 1989 Miura et al, electrostatic attraction by sparks due to airU.S. Pat. No. 4,810,954 accelerates the ink breakdown Tone-jet towardsthe print Required field medium. strength increases as the drop sizedecreases High voltage drive transistors required Electrostatic fieldattracts dust Permanent An electromagnet Low power Complex IJ07, IJ10magnet directly attracts a consumption fabrication electro- permanentmagnet, Many ink types Permanent magnetic displacing ink and can be usedmagnetic material causing drop ejection. Fast operation such asNeodymium Rare earth magnets High efficiency Iron Boron (NdFeB) with afield strength Easy extension required. around 1 Tesla can be fromsingle nozzles High local used. Examples are: to pagewidth printcurrents required Samarium Cobalt heads Copper (SaCo) and magneticmetalization should materials in the be used for long neodymium ironboron electromigration family (NdFeB, lifetime and low NdDyFeBNb,resistivity NdDyFeB, etc) Pigmented inks are usually infeasibleOperating temperature limited to the Curie temperature (around 540 K)Soft A solenoid induced a Low power Complex IJ01, IJ05, IJ08, magneticmagnetic field in a soft consumption fabrication IJ10, IJ12, IJ14, coreelectro- magnetic core or yoke Many ink types Materials not IJ15, IJ17magnetic fabricated from a can be used usually present in a ferrousmaterial such Fast operation CMOS fab such as as electroplated iron Highefficiency NiFe, CoNiFe, or alloys such as CoNiFe Easy extension CoFeare required [1], CoFe, or NiFe from single nozzles High local alloys.Typically, the to pagewidth print currents required soft magneticmaterial heads Copper is in two parts, which metalization should arenormally held be used for long apart by a spring. electromigration Whenthe solenoid is lifetime and low actuated, the two parts resistivityattract, displacing the Electroplating is ink. required High saturationflux density is required (2.0-2.1 T is achievable with CoNiFe[1]) LorenzThe Lorenz force Low power Force acts as a IJ06, IJ11, IJ13, forceacting on a current consumption twisting motion IJ16 carrying wire in aMany ink types Typically, only a magnetic field is can be used quarterof the utilized. Fast operation solenoid length This allows the Highefficiency provides force in a magnetic field to be Easy extensionuseful direction supplied externally to from single nozzles High localthe print head, for to pagewidth print currents required example withrare heads Copper earth permanent metalization should magnets. be usedfor long Only the current electromigration carrying wire need belifetime and low fabricated on the print- resistivity head, simplifyingPigmented inks materials are usually requirements. infeasible Magneto-The actuator uses the Many ink types Force acts as a Fischenbeck,striction giant magnetostrictive can be used twisting motion U.S. Pat.No. 4,032,929 effect of materiaLs Fast operation Unusual IJ25 such asTerfenol-D (an Easy extension materials such as alloy of terbium, fromsingLe nozzles Terfenol-D are dysprosium and iron to pagewidth printrequired developed at the Naval heads High local Ordnance Laboratory,High force is currents required hence Ter-Fe-NOL). available Copper Forbest efflciency, the metalization should actuator should be pre- be usedfor long stressed to approx. 8 eLectromigration MPa. lifetime and lowresistivity Pre-stressing may be required Surface Ink under positive Lowpower Requires Silverbrook, EP tension pressure is held in a consumptionsupplementary force 0771 658 A2 and reduction nozzle by surface Simpleto effect drop related patent tension. The surface constructionseparation applications tension of the ink is No unusual Requiresspecial reduced below the materials required in ink surfactants bubblethreshold, fabrication Speed may be causing the ink to High efficiencylimited by surfactant egress from the Easy extension properties nozzle.from single nozzles to pagewidth print heads Viscosity The ink viscosityis Simple Requires Silverbrook, EP reduction locally reduced toconstruction supplementary force 0771 658 A2 and select which drops areNo unusual to effect drop related patent to be ejected. A materialsrequired in separation applications viscosity reduction can fabricationRequires special be achieved Easy extension ink viscosityelectrothermally with from single nozzles properties most inks, butspecial to pagewidth print High speed is inks can be engineered headsdifficult to achieve for a 100:1 viscosity Requires reduction.oscillating ink pressure A high temperature difference (typicaily 80degrees) is required Acoustic An acoustic wave is Can operate Complexdrive 1993 Hadimioglu generated and without a nozzle circuitry et al,EUP 550,192 focussed upon the plate Complex 1993 EIrod et al, dropejection region. fabrication EUP 572,220 Low efficiency Poor control ofdrop position Poor control of drop volume Thermo- An actuator which Lowpower Efficient aqueous IJ03, IJ09, IJ17, elastic bend relies upondifferential consumption operation requires a IJ18, IJ19, IJ20, actuatorthermal expansion Many ink types thermal insulator on IJ21, IJ22, IJ23,upon Joule heating is can be used the hot side IJ24, IJ27, IJ28, used.Simple planar Corrosion IJ29, IJ30, IJ31, fabrication prevention can beIJ32, IJ33, 1334, Small chip area difficult IJ35, IJ36, IJ37, requiredfor each Pigmented inks IJ38, IJ39, IJ40, actuator may be infeasible,1341 Fast operation as pigment particles High efficiency may jam thebend CMOS actuator compatible voltages and currents Standard MEMSprocesses can be used Easy extension from single nozzles to pagewidthprint heads High CTE A material with a very High force can Requiresspecial IJ09, IJ17, IJ18, thermo- high coefficient of be generatedmaterial (e.g. PTFE) IJ20, IJ21, IJ22, elastic thermal expansion Threemethods of Requires a PTFE IJ23, IJ24, IJ27, actuator (CTE) such as PTFEdeposition are deposition process, IJ28, IJ29, IJ30,polytetrafluoroethylene under development: which is not yet IJ31, IJ42,IJ43, (PTFE) is used. As chemical vapor standard in ULSI IJ44 high CTEmateriats deposition (CVD), fabs are usually non- spin coating, and PTFEdeposition conductive, a heater evaporation cannot be followedfabricated from a PTFE is a with high conductive material is candidatefor low temperature (above incorporated. A 50 μm dielectric constant350° C.) processing long PTFE bend insulation in ULSI Pigmented inksactuator with Very low power may be infeasible, polysilicon heater andconsumption as pigment particles 15 mW power input Many ink types mayjam the bend can provide 180 μN can be used actuator force and 10 μmSimple planar deflection. Actuator fabrication motions include: Smallchip area Bend required for each Push actuator Buckle Fast operationRotate High efflciency CMOS compatible voltages and currents Easyextension from single nozzles to pagewidth print heads Conductive Apolymer with a high High force can Requires special IJ24 polymercoefficient of thermal be generated materials thermo- expansion (such asVery low power development (High elastic PTFE) is doped with consumptionCTE conductive actuator conducting substances Many ink types polymer) toincrease its can be used Requires a PTFE conductivity to about 3 Simpleplanar deposition process, orders of magnitude fabrication which is notyet below that of copper. Small chip area standard in ULSI Theconducting required for each fabs polymer expands actuator PTFEdeposition when resistively Fast operation cannot be followed heated.High efficiency with high Examples of CMOS temperature (above conductingdopants compatible voitages 350° C.) processing include: and currentsEvaporation and Carbon nanotubes Easy extension CVD deposition Metalfibers from single nozzles techniques cannot Conductive polymers topagewidth print be used such as doped beads Pigmented inks polythiophenemay be infeasible, Carbon granules as pigment particles may jam the bendactuator Shape A shape memory alloy High force is Fatigue limits IJ26memory such as TiNi (also available (stresses maximum number alloy knownas Nitinol - of hundreds of MPa) of cycles Nickel Titanium alloy Largestrain is Low strain (1%) developed at the Naval available (more than isrequired to extend Ordnance Laboratory) 3%) fatigue resistance isthermally switched High corrosion Cycle rate between its weak resistancelimited by heat martensitic state and Simple removal its high stiffnessconstruction Requires unusual austenic state. The Easy extensionmaterials (TiNi) shape of the actuator from single nozzles The latentheat of in its martensitic state to pagewidth print transformation mustis deformed relative to heads be provided the austenic shape. Lowvoltage High current The shape change operation operation causesejection of a Requires pre- drop. stressing to distort the martensiticstate Linear Linear magnetic Linear Magnetic Requires unusual IJ12Magnetic actuators include the actuators can be semiconductor ActuatorLinear Induction constructed with materials such as Actuator (LIA),Linear high thrust, long soft magnetic alloys Permanent Magnet travel,and high (e.g. CoNiFe) Synchronous Actuator efficiency using Somevarieties (LPMSA), Linear planar also require Reluctance semiconductorpermanent magnetic Synchronous Actuator fabrication materials such as(LRSA), Linear techniques Neodymium iron Switched Reluctance Longactuator boron (NdFeB) Actuator (LSRA), and travel is available Requiresthe Linear Stepper Medium force is complex multi- Actuator (LSA).available phase drive circuitry Low voltage High current operationoperation BASIC OPERATION MODE Actuator This is the simplest Simpleoperation Drop repetition Thermal ink jet directly mode of operation:the No external rate is usually Piezoelectric ink pushes ink actuatordirectly fields required limited to around 10 jet supplies sufficientSatellite drops kHz. However, this IJ01, IJ02, IJ03, kinetic energy toexpel can be avoided if is not fundamental IJ04, IJ05, IJ06, the drop.The drop drop velocity is less to the method, but is IJ07, 1309, IJ11,must have a sufficient than 4 m/s related to the refill IJ12, IJ14,IJ16, velocity to overcome Can be efficient, method normally IJ20, IJ22,IJ23, the surface tension. depending upon the used IJ24, IJ25, IJ26,actuator used All of the drop IJ27, IJ28, IJ29, kinetic energy mustIJ30, IJ31, IJ32, be provided by the IJ33, IJ34, IJ35, actuator IJ36,IJ37, IJ38, Satellite drops IJ39, IJ40, IJ41, usually form if drop IJ42,IJ43, IJ44 velocity is greater than 4.5 m/s Proximity The drops to beVery simple print Requires close Silverbrook, EP printed are selected byhead fabrication can proximity between 0771 658 A2 and some manner (e.g.be used the print head and related patent thermally induced The drop theprint media or applications surface tension selection means transferroller reduction of does not need to May require two pressurized ink).provide the energy print heads printing Selected drops are required toseparate alternate rows of the separated from the ink the drop from theimage in the nozzle by nozzle Monolithic color contact with the printprint heads are medium or a transfer difficult roller. Electro- Thedrops to be Very simple print Requires very Silverbrook, EP static pullprinted are selected by head fabrication can high electrostatic 0771 658A2 and on ink some manner (e.g. be used field related patent thermallyinduced The drop Electrostatic field applications surface tensionselection means for small nozzle Tone-Jet reduction of does not need tosizes is above air pressurized ink). provide the energy breakdownSelected drops are required to separate Electrostatic field separatedfrom the ink the drop from the may attract dust in the nozzle by anozzle strong electric field. Magnetic The drops to be Very simple printRequires Silverbrook, EP pull on ink printed are selected by headfabrication can magnetic ink 0771 658 A2 and some manner (e.g. be usedInk colors other related patent thermally induced The drop than blackare applications surface tension selection means difficult reduction ofdoes not need to Requires very pressurized ink). provide the energy highmagnetic fields Selected drops are required to separate separated fromthe ink the drop from the in the nozzle by a nozzle strong magneticfield acting on the magnetic ink. Shutter The actuator moves a Highspeed (>50 Moving parts are IJ13, IJ17, IJ21 shutter to block ink kHz)operation can required flow to the nozzle. The be achieved due toRequires ink ink pressure is pulsed reduced refill time pressuremodulator at a multiple of the Drop timing can Friction and wear dropejection be very accurate must be considered frequency. The actuatorStiction is energy can be very possible low Shuttered The actuator movesa Actuators with Moving parts are IJ08, IJ15, IJ18, grill shutter toblock ink small travel can be required IJ19 flow through a grill to usedRequires ink the nozzle. The shutter Actuators with pressure modulatormovement need only small force can be Friction and wear be equal to thewidth used must be considered of the grill holes. High speed (>50Stiction is kHz) operation can possible be achieved Pulsed A pulsedmagnetic Extremely low Requires an IJ10 magnetic field attracts an ‘inkenergy operation is external pulsed pull on ink pusher’ at the droppossible magnetic field pusher ejection frequency. An No heat Requiresspecial actuator controls a dissipation materials for both catch, whichprevents problems the actuator and the the ink pusher from ink pushermoving when a drop is Complex not to be ejected. construction AUXILIARYMECHANISM (APPLIED TO ALL NOZZLES) None The actuator directly Simplicityof Drop ejection Most ink jets, fires the ink drop, and constructionenergy must be including there is no external Simplicity of supplied bypiezoelectric and field or other operation individual nozzle thermalbubble. mechanism required. Small physical actuator IJ01, IJ02, IJ03,size IJ04, IJ05, IJ07, IJ09, IJ11, IJ12, IJ14, IJ20, IJ22, IJ23, IJ24,IJ25, IJ26, IJ27, IJ28, IJ29, IJ30, IJ31, IJ32, IJ33, IJ34, IJ35, IJ36,IJ37, IJ38, IJ39, IJ40, IJ41, IJ42, IJ43, IJ44 Oscillating The inkpressure Oscillating ink Requires external Silverbrook, EP ink pressureoscillates, providing pressure can provide ink pressure 0771 658 A2 and(including much of the drop a refill pulse, oscillator related patentacoustic ejection energy. The allowing higher Ink pressure applicationsstimul- actuator selects which operating speed phase and amplitude IJ08,IJ13, IJ15, ation) drops are to be fired The actuators must be carefullyIJ17, IJ18, IJ19, by selectively may operate with controlled IJ21blocking or enabling much lower energy Acoustic nozzles. The inkAcoustic lenses reflections in the ink pressure oscillation can be usedto focus chamber must be may be achieved by the sound on the designedfor vibrating the print nozzles head, or preferably by an actuator inthe ink supply. Media The print head is Low power Precision Silverbrook,EP proximity placed in close High accuracy assembly required 0771 658 A2and proximity to the print Simple print head Paper fibers may relatedpatent medium. Selected construction cause problems applications dropsprotrude from Cannot print on the print head further rough substratesthan unselected drops, and contact the print medium. The drop soaks intothe medium fast enough to cause drop separation. Transfer Drops areprinted to a High accuracy Bulky Silverbrook, EP roller transfer rollerinstead Wide range of Expensive 0771 658 A2 and of straight to the printprint substrates can Complex related patent medium. A transfer be usedconstruction applications roller can also be used Ink can be driedTektronix hot for proximity drop on the transfer roller meltpiezoelectric separation. inkjet Any of the IJ series Electro- Anelectric field is Low power Field strength Silverbrook, EP static usedto accelerate Simple print head required for 0771 658 A2 and selecteddrops towards construction separation of small related patent the printmedium. drops is near or applications above air Tone-Jet breakdownDirect A magnetic field is Low power Requires Silverbrook, EP magneticused to accelerate Simple print head magnetic ink 0771 658 A2 and fieldselected drops of construction Requires strong related patent magneticink towards magnetic field applications the print medium. Cross Theprint head is Does not require Requires external IJ06, IJ16 magneticplaced in a constant magnetic materials magnet field magnetic field. Theto be integrated in Current densities Lorenz force in a the print headmay be high, current caryying wire manufacturing resulting in is used tomove the process electromigration actuator. problems Pulsed A pulsedmagnetic Very low power Complex print IJ10 magnetic field is used tooperation is possible head construction field cyclically attract a Smallprint head Magnetic paddle, which pushes size materials required in onthe ink. A small print head actuator moves a catch, which selectivelyprevents the paddle from moving. ACTUATOR AMPLIFICATION OR MODIFICATIONMETHOD None No actuator Operational Many actuator Thermal Bubblemechanical simplicity mechanisms have Ink jet amplification is used.insufficient travel, IJ01, IJ02, IJ06, The actuator directly orinsufficient force, IJ07, IJ16, IJ25, drives the drop to efficientlydrive IJ26 ejection process. the drop ejection process Differential Anactuator material Provides greater High stresses are Piezoelectric.expansion expands more on one travel in a reduced involved IJ03, IJ09,IJ17, bend side than on the other. print head area Care must be IJ18,IJ19, IJ20, actuator The expansion may be taken that the IJ21, IJ22,IJ23, thermal, piezoelectric, materials do not IJ24, IJ27, IJ29,magnetostrictive, or delaminate IJ30, IJ31, IJ32, other mechanism. TheResidual bend IJ33, IJ34, IJ35, bend actuator converts resulting fromhigh IJ36, IJ37, IJ38, a high force low travel temperature or high IJ39,IJ42, IJ43, actuator mechanism to stress during IJ44 high travel, lowerformation force mechanism. Transient A trilayer bend Very good Highstresses are IJ40, IJ41 bend actuator where the two temperaturestability involved actuator outside layers are High speed, as a Caremust be identical. This cancels new drop can be taken that the bend dueto ambient fired before heat materials do not temperature and dissipatesdelaminate residual stress. The Cancels residual actuator only respondsstress of formation to transient heating of one side or the other.Reverse The actuator loads a Better coupling Fabrication IJ05, IJ11spring spring. When the to the ink complexity actuator is turned off,High stress in the the spring releases. spring This can reverse theforce/distance curve of the actuator to make it compatible with theforce/time requirements of the drop ejection. Actuator A series of thinIncreased travel Increased Some stack actuators are stacked. Reduceddrive fabrication piezoelectric inkjets This can be voltage complexityIJ04 appropriate where Increased actuators require high possibility ofshort electric field strength, circuits due to such as electrostaticpinholes and piezoelectric actuators. Multiple Multiple smallerIncreases the Actuator forces IJ12, IJ13, IJ18, actuators actuators areused force available from may not add IJ20, IJ22, IJ28, simultaneouslyto an actuator linearly, reducing IJ42, IJ43 move the ink. Each Multipleefficiency actuator need provide actuators can be only a portion of thepositioned to control force required. ink flow accurately Linear Alinear spring is used Matches low Requires print IJ15 Spring totransform a motion travel actuator with head area for the with smalltravel and higher travel spring high force into a requirements longertravel, lower Non-contact force motion. method of motion transformationCoiled A bend actuator is Increases travel Generally IJ17, IJ21, IJ34,actuator coiled to provide Reduces chip restricted to planar IJ35greater travel in a area implementations reduced chip area. Planar dueto extreme implementations are fabrication ditficulty relatively easy toin other orientations. fabricate. Flexure A bend actuator has a Simplemeans of Care must be IJ10, IJ19, IJ33 bend small region near theincreasing travel of taken not to exceed actuator fixture point, which abend actuator the elastic limit in flexes much more the flexure areareadily than the Stress remainder of the distribution is very actuator.The actuator uneven flexing is effectively Difficult to converted froman accurately model even coiling to an with finite element angular bend,resulting analysis in greater travel of the actuator tip. Catch Theactuator controls a Very low Complex IJ10 small catch. The catchactuator energy construction either enables or Very small Requiresexternal disables movement of actuator size force an ink pusher that isUnsuitable for controlled in a bulk pigmented inks manner. Gears Gearscan be used to Low force, low Moving parts are IJ13 increase travel atthe travel actuators can required expense of duration. be used Severalactuator Circular gears, rack Can be fabricated cycles are required andpinion, ratchets, using standard More complex and other gearing surfaceMEMS drive electronics methods can be used. processes Complexconstruction Friction, friction, and wear are possible Buckle plate Abuckle plate can be Very fast Must stay within S. Hirata et al, used tochange a slow movement elastic limits of the “An Ink-jet Head actuatorinto a fast achievable materials for long Using Diaphragm motion. It canalso device life Microactuator”, convert a high force, High stressesProc. IEEE MEMS, low travel actuator involved Feb. 1996, pp 418- into ahigh travel, Generally high 423. medium force motion. power requirementIJ18, IJ27 Tapered A tapered magnetic Linearizes the Complex IJ14magnetic pole can increase magnetic construction pole travel at theexpense force/distance curve of force. Lever A lever and fulcrum isMatches low High stress IJ32, IJ36, IJ37 used to transform a travelactuator with around the fulcrum motion with small higher travel traveland high force requirements into a motion with Fulcrum area has longertravel and no linear movement, lower force. The lever and can be usedfor can also reverse the a fluid seal direction of travel. Rotary Theactuator is High mechanical Complex IJ28 impeller connected to a rotaryadvantage construction impeller. A small The ratio of force Unsuitablefor angular deflection of to travel of the pigmented inks the actuatorresults in actuator can be a rotation of the matched to the impellervanes, which nozzle requirements push the ink against by varying thestationary vanes and number of impeller out of the nozzle. vanesAcoustic A refractive or No moving parts Large area 1993 Hadimioglu lensdiffractive (e.g. zone required et al, EUP 550,192 plate) acoustic lensis Only relevant for 1993 Elrod et al, used to concentrate acoustic inkjets EUP 572,220 sound waves. Sharp A sharp point is used SimpleDifficult to Tone-jet conductive to concentrate an constructionfabricate using point electrostatic field. standard VLSI processes for asurface ejecting ink- jet Only relevant for electrostatic ink jetsACTUATOR MOTION Volume The volume of the Simple High energy isHewlett-Packard expansion actuator changes, construction in thetypically required to Thermal Ink jet pushing the ink in all case ofthermal ink achieve volume Canon Bubblejet directions. jet expansion.This leads to thermal stress, cavitation, and kogation in thermal inkjet implementations Linear, The actuator moves in Efficient Highfabrication IJ01, IJ02, IJ04, normal to a direction normal to couplingto ink complexity may be IJ07, IJ11, IJ14 chip surface the print headsufface. drops ejected required to achieve The nozzle is typicallynormal to the perpendicular in the line of surface motion movement.Parallel to The actuator moves Suitable for Fabrication IJ12, IJ13,IJ15, chip surface parallel to the print planar fabrication complexityIJ33, , IJ34, IJ35, head surface. Drop Friction IJ36 ejection may stillbe Stiction normal to the surface. Membrane An actuator with a Theeffective Fabrication 1982 Howkins push high force but small area of theactuator complexity U.S. Pat. No. 4,459,601 area is used to push abecomes the Actuator size stiff membrane that is membrane areaDifficulty of in contact with the ink. integration in a VLSI processRotary The actuator causes Rotary levers Device IJ05, IJ08, IJ13, therotation of some may be used to complexity IJ28 element, such a grill orincrease travel May have impeller Small chip area friction at a pivotrequirements point Bend The actuator bends A very small Requires the1970 Kyser et al when energized. This change in actuator to be made U.S.Pat. No. 3,946,398 may be due to dimensions can be from at least two1973 Stemme differential thermal converted to a large distinct layers,or to U.S. Pat. No. 3,747,120 expansion, motion. have a thermal IJ03,IJ09, IJ10, piezoelectric difference across the IJ19, IJ23, IJ24,expansion, actuator IJ25, IJ29, IJ30, magnetostriction, or IJ31, IJ33,IJ34, other form of relative IJ35 dimensional change. Swivel Theactuator swivels Allows operation Inefficient IJ06 around a centralpivot. where the net linear coupling to the ink This motion is suitableforce on the paddle motion where there are is zero opposite forces Smallchip area applied to opposite requirements sides of the paddle, e.g.Lorenz force. Straighten The actuator is Can be used with Requirescareful IJ26, IJ32 normally bent, and shape memory balance of stressesstraightens when alloys where the to ensure that the energized. austenicphase is quiescent bend is planar accurate Double The actuator bends inOne actuator can Difficult to make IJ36, IJ37, IJ38 bend one directionwhen be used to power the drops ejected by one element is two nozzles.both bend directions energized, and bends Reduced chip identical. theother way when size. A small another element is Not sensitive toefficiency loss energized. ambient temperature compared to equivalentsingie bend actuators. Shear Energizing the Can increase the Not readily1985 Fishbeck actuator causes a shear effective travel of applicable toother U.S. Pat. No. 4,584,590 motion in the actuator piezoelectricactuator material. actuators mechanisms Radial con- The actuatorsqueezes Relatively easy High force 1970 Zoltan U.S. Pat. No. strictionan ink reservoir, to fabricate single required 3,683,212 forcing inkfrom a nozzles from glass Inefficient constricted nozzle. tubing asDifficult to macroscopic integrate with VLSI structures processesCoil/uncoil A coiled actuator Easy to fabricate Difficult to IJ17, IJ21,IJ34, uncoils or coils more as a planar VLSI fabricate for non- IJ35tightly. The motion of process planar devices the free end of the Smallarea Poor out-of-plane actuator ejects the ink. required, thereforestiffness low cost Bow The actuator bows (or Can increase the Maximumtravel IJ16, IJ18, IJ27 buckles) in the middle speed of travel isconstrained when energized. Mechanicaily High force rigid requiredPush-Pull Two actuators control The structure is Not readily IJ18 ashutter. One actuator pinned at both ends, suitable for ink jets pullsthe shutter, and so has a high out-of- which directly push the otherpushes it. plane rigidity the ink Curl A set of actuators curl Goodfluid flow Design IJ20, IJ42 inwards inwards to reduce the to the regionbehind complexity volume of ink that the actuator they enclose.increases efficiency Curl A set of actuators curl Relatively simpleRelatively large IJ43 outwards outwards, pressurizing construction chiparea ink in a chamber surrounding the actuators, and expelling ink froma nozzle in the chamber. Iris Multiple vanes enclose High efflciencyHigh fabrication IJ22 a volume of ink. These Small chip area complexitysimultaneously rotate, Not suitable for reducing the volume pigmentedinks between the vanes. Acoustic The actuator vibrates The actuator canLarge area 1993 Hadimioglu vibration at a high frequency. be physicallydistant required for et al, EUP 550,192 from the ink efficient operation1993 Elrod et al, at useful frequencies EUP 572,220 Acoustic couplingand crosstalk Complex drive circuitry Poor control of drop volume andposition None In various ink jet No moving parts Various otherSilverbrook, EP designs the actuator tradeoffs are 0771 658 A2 and doesnot move. required to related patent eliminate moving applications partsTone-jet NOZZLE REFILL METHOD Surface This is the normal way FabricationLow speed Thermal ink jet tension that ink jets are simplicity Surfacetension Piezoelectric ink refilled. After the Operational forcerelatively jet actuator is energized, simplicity small compared toIJ01-IJ07, IJ10- it typically returns actuator force IJ14, IJ16, IJ20,rapidly to its normal Long refill time IJ22-IJ45 position. This rapidusually dominates return sucks in air the total repetition through thenozzle rate opening. The ink surface tension at the nozzle then exerts asmall force restoring the meniscus to a minimum area. This force refillsthe nozzle. Shuttered Ink to the nozzle High speed Requires IJ08, IJ13,IJ15, oscillating chamber is provided at Low actuator common ink IJ17,IJ18, IJ19, ink pressure a pressure that energy, as the pressureoscillator IJ21 oscillates at twice the actuator need only May not bedrop ejection open or close the suitable for frequency. When a shutter,instead of pigmented inks drop is to be ejected, ejecting the ink dropthe shutter is opened for 3 half cycles: drop ejection, actuator return,and refill. The shutter is then closed to prevent the nozzle chamberemptying during the next negative pressure cycle. Refill After the mainHigh speed, as Requires two IJ09 actuator actuator has ejected a thenozzle is independent drop a second (refill) actively refilled actuatorsper nozzle actuator is energized. The refill actuator pushes ink intothe nozzle chamber. The refill actuator returns slowly, to prevent itsreturn from emptying the chamber again. Positive ink The ink is held aslight High refill rate, Surface spill Silverbrook, EP pressure positivepressure. therefore a high must be prevented 0771 658 A2 and After theink drop is drop repetition rate Highly related patent ejected, thenozzle is possible hydrophobic print applications chamber fills quicklyhead surfaces are Alternative for:, as surface tension and requiredIJ01-IJ07, IJ10-IJ14, ink pressure both IJ16, IJ20, IJ22-IJ45 operate torefill the nozzle. METHOD OF RESTRICTING BACK-FLOW THROUGH INLET Longinlet The ink inlet channel Design simplicity Restricts refill Thermalink jet channel to the nozzle chamber Operational rate Piezoelectric inkis made long and simplicity May result in a jet relatively narrow,Reduces relatively large chip IJ42, IJ43 relying on viscous crosstalkarea drag to reduce inlet Only partially back-flow. effective Positiveink The ink is under a Drop selection Requires a Silverbrook, EPpressure positive pressure, so and separation method (such as a 0771 658A2 and that in the quiescent forces can be nozzle rim or related patentstate some of the ink reduced effective applications drop alreadyprotrudes Fast refill time hydrophobizing, or Possible from the nozzle.both) to prevent operation of the This reduces the flooding of thefollowing: IJ01- pressure in the nozzle ejection surface of IJ07,IJ09-IJ12, chamber which is the print head. IJ14, IJ16, IJ20, requiredto eject a IJ22, , IJ23-IJ34, certain volume of ink. IJ36-IJ41, IJ44 Thereduction in chamber pressure results in a reduction in ink pushed outthrough the inlet. Baffle One or more baffles The refill rate is DesignHP Thermal Ink are placed in the inlet not as restricted as complexityJet ink flow. When the the long inlet May increase Tektronix actuator isenergized, method. fabrication piezoelectric ink jet the rapid inkReduces complexity (e.g. movement creates crosstalk Tektronix hot melteddies which restrict Piezoelectric print the flow through the heads).inlet. The slower refill process is unrestricted, and does not result ineddies. Flexible flap In this method recently Significantly Notapplicable to Canon restricts disclosed by Canon, reduces back-flow mostink jet inlet the expanding actuator for edge-shooter configurations(bubble) pushes on a thermal ink jet Increased flexible flap thatdevices fabrication restricts the inlet. complexity Inelasticdeformation of polymer flap results in creep over extended use Inletfilter A filter is located Additional Restricts refill IJ04, IJ12, IJ24,between the ink inlet advantage of ink rate IJ27, IJ29, IJ30 and thenozzle filtration May result in chamber. The filter Ink filter may becomplex has a multitude of fabricated with no construction small holesor slots, additional process restricting ink flow. steps The filter alsoremoves particles which may block the nozzle. Small inlet The ink inletchannel Design simplicity Restricts refill IJ02, IJ37, IJ44 compared tothe nozzle chamber rate to nozzle has a substantially May result in asmaller cross section relatively large chip than that of the nozzle arearesulting in easier ink Only partially egress out of the effectivenozzle than out of the inlet. Inlet shutter A secondary actuatorIncreases speed Requires separate IJ09 controls the position of of theink-jet print refill actuator and a shutter, closing off head operationdrive circuit the ink inlet when the main actuator is energized. Theinlet is The method avoids the Back-flow Requires careful IJ01, IJ03,IJ05, located problem of inlet back- problem is design to minimize IJ06,IJ07, IJ10, behind the flow by arranging the eliminated the negativeIJ11, IJ14, IJ16, ink-pushing ink-pushing surface of pressure behind theIJ22, IJ23, IJ25, surface the actuator between paddle IJ28, IJ31, IJ32,the inlet and the IJ33, IJ34, IJ35, nozzle. IJ36, IJ39, IJ40, IJ41 Partof the The actuator and a Significant Small increase in IJ07, IJ20,IJ26, actuator wall of the ink reductions in back- fabrication IJ38moves to chamber are arranged flow can be complexity shut off the sothat the motion of achieved inlet the actuator closes off Compactdesigns the inlet. possible Nozzle In some configurations Ink back-flowNone related to Silverbrook, EP actuator of ink jet, there is no problemis ink back-flow on 0771 658 A2 and does not expansion or eliminatedactuation related patent result in ink movement of an applicationsback-flow actuator which may Valve-jet cause ink back-flow Tone-jetthrough the inlet. NOZZLE CLEARING METHOD Normal All of the nozzles areNo added May not be Most ink jet nozzle firing fired periodically,complexity on the sufficient to systems before the ink has a print headdisplace dried ink IJ01, IJ02, IJ03, chance to dry. When IJ04, IJ05,IJ06, not in use the nozzles IJ07, IJ09, IJ1O, are sealed (capped) IJ11,IJ12, IJ14, against air. IJ16, IJ20, IJ22, The nozzle firing is IJ23,IJ24, IJ25, usually performed IJ26, IJ27, IJ28, during a special IJ29,IJ30, IJ31, clearing cycle, after IJ32, IJ33, IJ34, first moving theprint IJ36, IJ37, IJ38, head to a cleaning IJ39, IJ40,, IJ41, station.IJ42, IJ43, IJ44,, IJ45 Extra In systems which heat Can be highlyRequires higher Silverbrook, EP power to the ink, but do not boileffective if the drive voltage for 0771 658 A2 and ink heater it undernormal heater is adjacent to clearing related patent situations, nozzlethe nozzle May require applications clearing can be larger driveachieved by over- transistors powering the heater and boiling ink at thenozzle. Rapid The actuator is fired in Does not require EffectivenessMay be used succession rapid succession. In extra drive circuits dependswith: IJ01, IJ02, of actuator some configurations, on the print headsubstantially upon IJ03, IJ04, IJ05, pulses this may cause heat Can bereadily the configuration of IJ06, IJ07, IJ09, build-up at the nozzlecontrolled and the ink jet nozzle IJ10, IJ11, IJ14, which boils the ink,initiated by digital IJ16, IJ20, IJ22, clearing the nozzle. In logicIJ23, IJ24, IJ25, other situations, it may IJ27, IJ28, IJ29, causesufficient IJ30, IJ31, IJ32, vibrations to dislodge IJ33, IJ34, IJ36,clogged nozzles. IJ37, IJ38, IJ39, IJ40, IJ41, IJ42, IJ43, IJ44, IJ45Extra Where an actuator is A simple Not suitable May be used power tonot normally driven to solution where where there is a with: IJ03, IJ09,ink pushing the limit of its motion, applicable hard limit to IJ16,IJ20, IJ23, actuator nozzle clearing may be actuator movement IJ24,IJ25, IJ27, assisted by providing IJ29, IJ30, IJ31, an enhanced driveIJ32, IJ39, IJ40, signal to the actuator. IJ41, IJ42, IJ43, IJ44, IJ45Acoustic An ultrasonic wave is A high nozzle High IJ08, IJ13, IJ15,resonance applied to the ink clearing capability implementation costIJ17, IJ18, IJ19, chamber. This wave is can be achieved if system doesnot IJ21 of an appropriate May be already include an amplitude andimplemented at very acoustic actuator frequency to cause low cost insystems sufficient force at the which already nozzle to clear includeacoustic blockages. This is actuators easiest to achieve if theultrasonic wave is at a resonant frequency of the ink cavity. Nozzle Amicrofabricated Can clear Accurate Silverbrook, EP clearing plate ispushed against severely clogged mechanical 0771 658 A2 and plate thenozzles. The plate nozzles alignment is related patent has a post forevery required applications nozzle. A post moves Moving parts arethrough each nozzle, required displacing dried ink. There is risk ofdamage to the nozzles Accurate fabrication is required Ink The pressureof the ink May be effective Requires May be used pressure is temporarilywhere other pressure pump or with all IJ series ink pulse increased sothat ink methods cannot be other pressure jets streams from all of theused actuator nozzles. This may be Expensive used in conjunctionWasteful of ink with actuator energizing. Print head A flexible ‘blade’is Effective for Difficult to use if Many ink jet wiper wiped across theprint planar print head print head surface is systems head surface. Thesurfaces non-planar or very blade is usually Low cost fragile fabricatedfrom a Requires flexible polymer, e.g. mechanical parts rubber orsynthetic Blade can wear elastomer. out in high volume print systemsSeparate A separate heater is Can be effective Fabrication Can be usedwith ink boiling provided at the nozzle where other nozzle complexitymany IJ series ink heater although the normal clearing methods jets drope-ection cannot be used mechanism does not Can be require it. Theheaters implemented at no do not require additional cost in individualdrive some ink jet circuits, as many configurations nozzles can becleared simultaneously, and no imaging is required. NOZZLE PLATECONSTRUCTION Electro- A nozzle plate is Fabrication High Hewlett Packardformed separately fabricated simplicity temperatures and Thermal Ink jetnickel from electroformed pressures are nickel, and bonded to requiredto bond the print head chip. nozzle plate Minimum thickness constraintsDifferential thermal expansion Laser Individual nozzle No masks Eachhole must Canon Bubblejet ablated or holes are ablated by an required beindividually 1988 Sercel et drilled intense UV laser in a Can be quitefast formed al., SPIE, Vol. 998 polymer nozzle plate, which is Somecontrol Special Excimer Beam typically a polymer over nozzle profileequipment required Applications, pp. such as polyimide or is possibleSlow where there 76-83 polysulphone Equipment are many thousands 1993Watanabe required is relatively of nozzles per print et al., U.S. Pat.No. low cost head 5,208,604 May produce thin burrs at exit holes SiliconA separate nozzle High accuracy is Two part K. Bean, IEEE micro- plateis attainable construction Transactions on machined micromachined fromHigh cost Electron Devices, single crystal silicon, Requires Vol. ED-25,No. 10, and bonded to the precision alignment 1978, pp 1185-1195 printhead wafer. Nozzles may be Xerox 1990 clogged by adhesive Hawkins etal., U.S. Pat. No. 4,899,181 Glass Fine glass capillaries No expensiveVery small 1970 Zoltan U.S. Pat. No. capillaries are drawn from glassequipment required nozzle sizes are 3,683,212 tubing. This method Simpleto make difficult to form has been used for single nozzles Not suitedfor making individual mass production nozzles, but is difficult to usefor bulk manufacturing of print heads with thousands of nozzles.Monolithic, The nozzle plate is High accuracy Requires Silverbrook, EPsurface deposited as a layer (<1 μm) sacrificial layer 0771 658 A2 andmicro- using standard VLSI Monolithic under the nozzle related patentmachined deposition techniques. Low cost plate to form the applicationsusing VLSI Nozzles are etched in Existing nozzle chamber IJ01, IJ02,IJ04, litho- the nozzle plate using processes can be Surface may beIJ11, IJ12, IJ17, graphic VLSI lithography and used fragile to the touchIJ18, IJ20, IJ22, processes etching. IJ24, IJ27, IJ28, IJ29, IJ30, IJ31,IJ32, IJ33, IJ34, IJ36, IJ37, IJ38, IJ39, IJ40, IJ41, IJ42, IJ43, IJ44Monolithic, The nozzle plate is a High accuracy Requires long IJ03,IJ05, IJ06, etched buried etch stop in the (<1 μm) etch times IJ07,IJ08, IJ09, through wafer. Nozzle Monolithic Requires a IJ10, IJ13,IJ14, substrate chambers are etched in Low cost support wafer IJ15,IJ16, IJ19, the front of the wafer, No differential IJ21, IJ23, IJ25,and the wafer is expansion IJ26 thinned from the back side. Nozzles arethen etched in the etch stop layer. No nozzle Various methods have Nonozzles to Difficult to Ricoh 1995 plate been tried to eliminate becomeclogged control drop Sekiya et al U.S. Pat. No. the nozzles entirely, toposition accurately 5,412,413 prevent nozzle Crosstalk 1993 Hadimiogluclogging. These problems et al EUP 550,192 include thermal bubble 1993Elrod et al mechanisms and EUP 572,220 acoustic lens mechanisms TroughEach drop ejector has Reduced Drop firing IJ35 a trough throughmanufacturing direction is sensitive which a paddle moves. complexity towicking. There is no nozzle Monolithic plate. Nozzle slit Theelimination of No nozzles to Difficult to 1989 Saito et al instead ofnozzle holes and become clogged control drop U.S. Pat. No. 4,799,068individual replacement by a slit position accurately nozzlesencompassing many Crosstalk actuator positions problems reduces nozzleclogging, but increases crosstalk due to ink surface waves DROP EJECTIONDIRECTION Edge Ink flow is along the Simple Nozzles limited CanonBubblejet (‘edge surface of the chip, construction to edge 1979 Endo etal GB shooter’) and ink drops are No silicon High resolution patent2,007,162 ejected from the chip etching required is difficult Xeroxheater-in- edge. Good heat Fast color pit 1990 Hawkins et sinking viasubstrate printing requires al U.S. Pat. No. 4,899,181 Mechanically oneprint head per Tone-jet strong color Ease of chip handing Surface Inkflow is along the No bulk silicon Maximum ink Hewlett-Packard (‘roofsurface of the chip, etching required flow is severely TIJ 1982 Vaughtet shooter’) and ink drops are Silicon can make restricted al U.S. Pat.No. 4,490,728 ejected from the chip an effective heat IJ02, IJ11, IJ12,surface, normal to the sink IJ20, IJ22 plane of the chip. Mechanicalstrength Through Ink flow is through the High ink flow Requires bulkSilverbrook, EP chip, chip, and ink drops are Suitable for siliconetching 0771 658 A2 and forward ejected from the front pagewidth printrelated patent (‘up surface of the chip. heads applications shooter’)High nozzle IJ04, IJ17, IJ18, packing density IJ24, IJ27-IJ45 thereforelow manufacturing cost Through Ink flow is through the High ink flowRequires wafer IJ01, IJ03, IJ05, chip, chip, and ink drops are Suitablefor thinning IJ06, IJ07, IJ08, reverse ejected from the rear pagewidthprint Requires special IJ09, IJ10, IJ13, (‘down surface of the chip.heads handling during IJ14, IJ15, IJ16, shooter’) High nozzlemanufacture IJ19, IJ21, IJ23, packing density IJ25, IJ26 therefore lowmanufacturing cost Through Ink flow is through the Suitable forPagewidth print Epson Stylus actuator actuator, which is notpiezoelectric print heads require Tektronix hot fabricated as part ofheads several thousand melt piezoelectric the same substrate asconnections to drive ink jets the drive transistors. circuits Cannot bemanufactured in standard CMOS fabs Complex assembly required INK TYPEAqueous, Water based ink which Environmentally Slow drying Most existingink dye typically contains: friendly Corrosive jets water, dye,surfactant, No odor Bleeds on paper All IJ series ink humectant, and Mayjets biocide. strikethrough Silverbrook, EP Modern ink dyes have Cocklespaper 0771 658 A2 and high water-fastness, related patent lightfastnessapplications Aqueous, Water based ink which Environmentally Slow dryingIJ02, IJ04, IJ21, pigment typically contains: friendly Corrosive IJ26,IJ27, IJ30 water, pigment, No odor Pigment may Silverbrook, EPsurfactant, humectant, Reduced bleed clog nozzles 0771 658 A2 and andbiocide. Reduced wicking Pigment may related patent Pigments have anReduced clog actuator applications advantage in reduced strikethroughmechanisms Piezoelectric ink- bleed, wicking and Cockles paper jetsstrikethrough. Thermal ink jets (with significant restrictions) MethylMEK is a highly Very fast drying Odorous All IJ series ink Ethylvolatile solvent used Prints on various Flammable jets Ketone forindustrial printing substrates such as (MEK) on difficult surfacesmetals and plastics such as aluminum cans. Alcohol Alcohol based inksFast drying Slight odor All IJ series ink (ethanol, 2- can be used wherethe Operates at sub- Flammable jets butanol, printer must operate atfreezing and others) temperatures below temperatures the freezing pointof Reduced paper water. An example of cockle this is in-camera Low costconsumer photographic printing. Phase The ink is solid at No dryingtime- High viscosity Tektronix hot change room temperature, and inkinstantiy freezes Printed ink melt piezoelectric (hot melt) is melted inthe print on the print medium typically has a ink jets head beforejetting. Almost any print ‘waxy’ feel 1989 Nowak Hot melt inks aremedium can be used Printed pages U.S. Pat. No. 4,820,346 usually waxbased, No paper cockle may ‘block’ All IJ series ink with a meltingpoint occurs Ink temperature jets around 80° C. After No wicking may beabove the jetting the ink freezes occurs curie point of almost instantlyupon No bleed occurs permanent magnets contacting the print Nostrikethrough Ink heaters medium or a transfer occurs consume powerroller. Long warm-up time Oil Oil based inks are High solubility Highviscosity: All IJ series ink extensively used in medium for some this isa significant jets offset printing. They dyes limitation for use in haveadvantages in Does not cockle ink jets, which improved paper usuallyrequire a characteristics on Does not wick low viscosity. Some paper(especially no through paper short chain and wicking or cockle).multi-branched oils Oil soluble dies and have a sufficiently pigmentsare required. low viscosity. Slow drying Micro- A microemulsion is aStops ink bleed Viscosity higher All IJ series ink emulsion stable, selfforming High dye than water jets emulsion of oil, water, solubility Costis slightly and surfactant. The Water, oil, and higher than watercharacteristic drop size amphiphilic soluble based ink is less than 100nm, dies can be used High surfactant and is deterinined by Can stabilizeconcentration the preferred curvature pigment required (around of thesurfactant. suspensions 5%)

We claim:
 1. A print head recapping mechanism for recapping a page widthprint head structure, the recappino mechanism comprising; a first,stationary ferrous arm; a solenoid coil wound around a portion of saidferrous arm; a second, moveable arm juxtaposed with said first arm andbiased towards said print head structure, the moveable arm beingdisplaceable between a first, rest position and a second position; and asealing means attached to said second, moveable arm, said sealing meanssealing said print head structure when said moveable arm is in its restposition, said solenoid being activated to cause said moveable arm tomove to its second position away from a surface of said print headstructure with sufficient clearance to allow print media to be insertedbetween said sealing means and said print head structure for theprinting of ink on said print media, a magnitude of current required todisplace the moveable arm from its first position to its second positionbeing greater than a magnitude of current required to retain themoveable arm at its second position.
 2. A print head recapping mechanismas claimed in claim 1 wherein said sealing means comprises a resilientlyflexible web which stands proud of a surface of the second, moveable armto seal against the surface of the print head structure when the second,moveable arm is in its first position.
 3. A print head recappingmechanism as claimed in claim 2 wherein said sealing means furthercomprises an elastomeric member running substantially the length of anink jet chip of said print head structure, the elastomeric member beingsurrounded by the flexible web.
 4. A print head recapping mechanism asclaimed in claim 1 wherein said solenoid comprises an elongated windingof a current carrying wire which is wrapped around a protruding portionof said first arm, said elongated winding being substantially the lengthof said print head structure.
 5. A print head recapping mechanism asclaimed in claim 1 wherein said second movable arm is biased against thesurface of said print head structure.
 6. A print head recappingmechanism as claimed in claim 1 wherein said mechanism is utilized in ahand held camera device.
 7. A method of operating a hand held cameradevice having a printhead for printing on a roll of print media, saidprint head including a recapping mechanism and a paper cuttingmechanism, the method comprising the steps of: activating said recappingmechanism to move said mechanism away from said printhead so as to allowfor printing by said printhead on print media; printing an image on saidprint media; cutting said print media on a border of said image so as toform a detachable separate image; rewinding said roll print media sothat said print media clears the space between said printhead and saidrecapping mechanism; and deactivating said recapping mechanism so thatit moves adjacent said printhead.